How they Compare: Itachi Uchiha

Itachi Uchiha was born to a world of war. At the age of 4 he saw the world ravaged by the Third Shinobi World War, an event that left him broken and wishing to find a way to end war. Itachi was born a Uchiha, a clan outcasted and hated by their villain due to suspicions of their power and their potential role in the Ninetails attack on the village. Itachi was however a hope for the Uchiha Clan. He was a peerless talent, with legendary accolades, surpassing the Chunin and the Jonin before even reaching his teenage years. He was always alone however. Many thought the lonely and mysterious Itachi was alone because his power distinguished him, but it was in truth a disdain for the world of the Shinobi around him, a world of war and death. 

For his talents he was allowed to sit on the highest rank meetings of the Uchiha Clan, finding that they planned to ensure a future for their clan in an uprising. Wanting to avoid this Itachi was a double agent, reporting too the Hokage of what he had seen, hoping they might find a peaceful resolution. However peace failed to win out. Danzo told Itachi the Uchiha planned to revolt and gave him an ultimatum. Join his clan in their uprising, and have them all be wiped out. Or, kill the clan himself, preserving their name and the rest of the village. The 13 year old Itachi agreed because he was given special permission to save one person, the person he cared for most, his little brother Sasuke. And thus Itachi who disdained death killed his own clan. Itachi began his plan there, playing the villain for Sasuke, telling him he did it merely to test his power, daring Sasuke to get strong enough to kill him. Itachi left the villain hated and feared. 

From there Itachi would join the criminal ninja group the Akatsuki as a double agent for the Village hidden in the Leaves, secretly protecting them. His plan worked, with Sasuke growing strong and capable out of hatred for Itachi, strong enough to face Itachi, strong enough to create a future for their clan. Itachi died in battle with Sasuke who had grown strong enough to become a leader of their nation. Yet when Itachi briefly from the grave he saw that Sasuke was planning to destroy the village for what they had done to Itachi and their clan, more senseless death, and realized he was wrong. Even as he returned to the afterlife he tried to impact a final lesson to Sasuke, that he had spent his life lying and being alone and that maybe if he had been willing to share his burdens then tragedy may have been prevented, and telling Sasuke that no matter what Itachi would love him always. 

Itachi possess the unique feature of his clan, the Sharingan which are a major feature in his Taijutsu, Ninjutsu, and Genjutsu. The Sharingan are special eyes awoken through extreme emotions divided into the Eye of Insight and the Eye of Hypnotism. The Eye of Insight grants extremely enhanced perception, enough to see through walls, see faint shadows in a heavy mist, and see things on the cellular level. Beyond that it allows most famously the ability to copy techniques it sees as well as see a bit into the future by predicting what will happen based on the current movement of things around, giving power mimicry and minor precog. It also sees through most illusions and can reflect them back on the user. 

Itachi has evolved his Sharingan to the most advanced level, the Mangekyo Sharingan. These enhance all of the prior abilites of the Sharingan and each eye grants an extremely powerful ability for Itachi's usage as well as the Susanoo granted to all Mangekyo Sharingan Users. However because they are not Eternal Mangekyo Shanringan they are very highly stamina draining and slowly drain the eyesight from the user until they go blind. 

Taijutsu which involves physical stats and martial arts skills is probably Itachi's least impressive quality and it's still extraordinarily impressive. For most of the story he is slowly dying of sickness and this Itachi is still considered one of the strongest members of the Akatsuki, to the point of being more then a match for a version of Sasuke then prior easily defeated Sasori, another Akatsuki member. The Akatsuki are a squad of elite criminal Ninja who hit down the Jinchuriki, Ninja hosts of the Biju, Kaiju Monsters made of Chakra. These Biju are capable of vaporizing their surrounding areas and creating mountain sized explosions calced into the gigatons. Itachi is likely in the range of the Kage Onoki who literally carried around Turtle Island and with some help from Gaara stopped Madara's meteor with likely gigaton to teraton level power. All of this is a weak sick Itachi. When he was brought back with his Edo Tensei, he was able to fight KCM Naruto directly who had a substantial amount of Kurama's chakra, Kurama being an an entity that could turn the world to ash and protect the Shinobi Alliance from the Tentails cataclysm calced as being in the petatons level. Even in KCM1 Naruto would likely be in the teraton range, consistent with Edo Tensei Itachi being likely far above his sick dying self who scales himself likely much below the weaker Jinchuriki. Even this was however was stated to be below Itachi at his prime. There's more feats that make this consistent as well.

In speed, Itachi even as he was dying out was able to block the Kirin which is a lightning Jutsu stated in databooks to move at lightspeed, though this is likely in part due to the Sharigan's precog and ability to fight faster opponents. He was still faster then Kakashi who was able to lightning-time even at a young age. Edo Itachi was able to match KCM1 Naruto in speed, albeit Naruto may not have been trying his absolute hardest. This is still impressive as KCM 1 Naruto had just recently shown the ability to outpace even the Raikage, the speedster of the era, who could move at lightspeed, suggesting Itachi would likely be nearing lightspeed. When he was alive, he'd likely be even faster. Itachi was also able to match Naruto in hand to hand skills temporarily, Naruto being so skilled in combat that even in Part 1 he was able to land hits on Sasuke despite Sasuke using the Sharingan to precog Naruto's movements through sheer skill alone. 

In terms of Ninjutsu while most Ninjas only learn one Elemental Release they have particular affinity for, Itachi has learned three of the five elemental styles. He is noted to known Wind Release and Water Release, the ability to create wind and water, able to use wind to increase the potency of fires and through water can shoot out water bullets at light speed or turning them viscous to trap foes. However what he is most known for is Fire Release, creating fire including normal and blue fireballs from his hands or breathed out. 

This is released to one of his two Mangekyo Sharingan abilities, Amaterasu. Amaterasu is said to be the highest level of Fire Release and the Most Powerful Physical Ability of the Mangekyo Sharingan, world ending flames, that scorches all things in Heaven and Earth. It can spawn anywhere Itachi can see, and will burn any target, even other flames or flameproof creatures, until the target is ash. Nothing, even water can extinguish them, and they will burn for seven days and seven nights. Itachi can also create a ring of it as a defensive technique. Given its description of scorching all things in Heaven and Earth, it may be able to hit incorporeal enemies like ghosts. 

Itachi is also highly proficient in both Yang and Yin Release, especially Yin Release and given his master status would likely possess a wide variety of Ninja abilities that are common to the verse such as as adhesion, shapeshifting, and switching his body with other objects. Itachi has actually learned the most famous high level technique in the entire series, Shadow Clone Jutsu allowing him to duplicate himself numerous times creating physical copies.

Itachi also has numerous other forms of clone techniques. In particular Itachi is most famous for his crows which he can summon, seal in other people, and see through. He has a particular technique known as Karasu Bushin no Jutsu where he forms a clone of himself from his crows. This has similar power to a Shadow Clone but requires far less chakra to maintain. 

Like all Uchiha who have awoken the Mangekyo Sharingan, Itachi also has access to the extremely powerful Ninjutsu, the Susanoo. The Susanoo manifests a giant humanoid Chakra Armor around the Ninja, the  greatly boosting their physical offenses and defenses. With his Susanoo and Amaterasu for instance, Sasuke was able to fight the 5 Kage, the greatest Ninjas of the 5 nations, and Itachi's experience with the techniques were superior to 5 Kage Summit Sasuke. Even then Itachi's Susanoo is special.

Itachi's Susanno has two legendary weapons. The First is the Tohska Blade, a spiritual blade that ignores durability and seals whoever is hit inside the Susanoo's jar in a state of drunken dreams. The other is the Yata Mirror, a shield that adapts to the properties of what is thrown at it to nullify incoming attacks, including attacks vastly stronger then Itachi. 

But more then his Taijutsu and even his Ninjutsu, Itachi is known for his Genjutsu, the Ninja Art of messing with their opponents' minds. Most Genjutsu requires eye contact but Itachi has two ways to bypass this. One is that because he can see through his crows, making eye contact with one of them gives the same effect. The other is that Itachi has a special Genjutsu called Ephemeral which he can use just by pointing at his opponent. Most Genjutsu is used for illusory purposes with Itachi's illusions so potent he can make Sasuke believe that Itachi pulled out Sasuke's eye, messing all his senses for an extended period. Itachi's Genjutsu is strong enough that it was believed he might be the source of various agents slipping past the Allied Shinobi Forces' sensory Ninjas across the war and was able to easily reverse the Genjutsu of Kurenai, a Genjutsu specialist back onto her. 

The Sharingan and especially the Mangekyo Sharingan can grant access to the more advanced uses of Genjutsu. This would include such things sending hundreds of people to sleep, inducing paralysis, inducing crippling fear even in people without emotions like Sai, read memories, and inflict massive pain. More then that the Sharingan has been used to control even the Tailed Beasts, giant monsters made of Chakra with which Obito used to control even the great Ninetails to attack the Village though how Itachi compares to this version of Obito in Genjutsu is unclear. Fugaku, father of Itachi and Sasuke believed he could in the anime, so Itachi may be able too at least briefly.

Itachi also has access to some of the most powerful Genjutsu techniques. His other Mangekyo ability is Tsukoyomi, a Genjutsu so powerful that despite being introduced early in the series, it remains in contention for the best Genjutsu in the series. Tsukuyomi allows Itachi to create a world in the mind of his opponent where he controls everything about the reality and can use it to try and mentally break his opponent. This ability creates an infinite sized mental reality and is a form of infinite potency mental hax, dedicated to causing so much mental strain that the person experiencing it so that their mind breaks. Unlike other Genjutsu someone outside can't break someone undergoing Tsukuyomi out of it as the effect happens instantly from their perspective, with whole lifetimes being able to be lived out in picoseconds. 

One of Itachi's crows also possesses the eye of Shisui which allows him to use extremely occasionally (once every 10 years) the ability of Kotoamatsukami which is a from of mind control that works by incredibly subtlety altering the way a person's minds forms thoughts, so subtle that the target doesn't realize anything is happening at all and doesn't trigger normal mental resistances. 

Itachi has also learned the ancient Uchiha technique of Izanami and likely its counterpart Izanagi. These are abilities that hypothetically any Sharigan user can learn but each one comes with the cost of one of their eyes so are last resort type moves. Izanagi is a Genjutsu cast on oneself that turns events that happened in reality into parts of a Genjutsu illusion instead, blurring the boundary between reality and illusion. It lasts for 60 seconds during which any unfavorable outcome in battle can be rewritten including having been killed which is how Madara escaped his death at the hands of Hashirama. 

Itachi is more known for his usage of the technique designed to counter Izanagi, Izanami. Izanami is a genjutsu technique that takes requires some time to set up but not eye contact and what it does is it causes the people trapped in the technique to undergo an infinite time loop of the events in the set up. Izanami is said to control fate itself and can only be broken out of if the target is able to accept their destiny rather then fighting against it, used to break the strongest of wills by by subjecting them to the infinitude of time that wears away wills.

Along with all his abilities, Itachi is also proficient in all the mundane skills that make a Ninja a Ninja, having completed 340 millions and with even the first Hokage Hashirama calling him a greater Ninja then he. Itachi has a huge suite of impressive feats such as being described as thinking like a Hokage by the age of 7, being promoted to the Anbu Black Ops directly unto the Hokage by age 12, figuring out strategies to defeat Nagato and Kabuto. In the latter case figuring out how to counter Shinra Tensei in seconds and in the latter case Kabuto's Edo Tensei was said to have no weaknesses only for Itachi to say that "every jutsu has a weakness... and the weakness of your jutsu is my existence." Itachi has been praised for his intelligence by many of the smartest characters in the series, was able to manipulate Sasuke over a grand master plan to make Sasuke a hero to the village and bring about the rebirth of their clan, and infiltrated the Akatsuki manipulating them to minimize collateral damage and protect the village hidden in the leaf over the years. He has a high degree of knowledge of the Ninja world, knowing of the legendary Izanagi and Izanami, can quickly analyze his opponents, and even Obito the leader of the Akatsuki thought that Itachi's preparation would have killed him with his post-mortem trap if he knew fully about Obito's abilities.  

Itachi has a mastery of all the normal ninja arts including stealth, sleight of hand, acrobatics, environmental manipulation, pressure point combat, various weapons, and control of one's Chakra. He also has a high willpower, strong enough that he could attack Obito despite Obito's fear aura. 

Itachi was also resurrected by the Edo Tensei along with most of the great ninjas in history during the War Arc. As an Edo Tensei, Itachi is a regenerating zombie ninja. The regeneration is on a low-godly scale with an Edo Tensei able to come back from complete destruction of their body so long as their soul still exists. Usually Edo Tensei are controlled by the caster of the Jutsu, in this case Kabuto, but Itachi though preparation used the Kotoamatsukami on himself to slip out of the control of and eventually defeat Kabuto himself. This form is particularly helpful for Itachi as is it mitigates his biggest weakness. 

Itachi's major weakness for most of the series is his lack of stamina. Not only do his most powerful techniques take a lot of Chakra, but over the series until his final fight he was slowly dying of a disease that gradually eroded his physical capabilities, his stamina in particular. This is compounded on how many of his techniques are focused around defeating one opponent very thoroughly, causing him to have more difficulty fighting numerous opponents at once. However this weakness is less potent in his Prime in Part 1 when he wasn't suffering from the disease or in his Edo State as Edos have seemingly infinite chakra. 

In addition, he has many of the common ninja weaknesses. His powers come from his Chakra and his Sharingan, and if he is drained of chakra, he only his the passive Sharingan abilities to rely on. Taijutsu requires melee range for the most part, Ninjutsu requires hand seals to use, and Genjutsu usually requires eye contact, though Itachi's ephemral is activated by pointing instead. Also most techniques have balancing drawbacks such as the Yata Mirror which can block any attack but is unidirectional meaning once again, multiple opponents or other multi-directional attacks can get past it

Name: Itachi Uchiha, Itachi of the Sharingan

Origin: Naruto

Powers and Abilities: Kage+ Ranked Naruto Ninja Abilities, Enhanced Vision, Technique Mimicry, Illusion Negation and Reflection, Elemental Manipulation (Fire, Water, and Wind. Can also summon the black flames of Amaterasu), Duplication, Animal Manipulation (Crows), Can summon a Chakra Armor Mech (Susanoo), Sealing (Totsuka Blade), Attack Reflection (Yata Mirror), Non-Physical Interaction Totsuka Blade and possibly Amaterasu), Mind Manipulation with Genjutsu (Various Forms including Illusions, Mind Manipulation, Emotion Manipulation, Memory Manipulation, Sleep Manipulation, Pain Inducement, and Paralysis Inducement), can trap his opponent in an infinite mental reality that Itachi controls to mentally break them (Tsukoyomi), Subtle Mind Control (Kotoamatsukami), Reality-Warping (Izanagi), Fate Manipulation (Izanami) | All of the Prior, Low Godly Regen, Zombie Physiology 

Weaknesses: Dying and Relatively Low Stamina in Part 2, individual techniques have various drawbacks such as most of his Genjutsu requiring eye contact, tends to hold back as he hates conflict and killing

Attack Potency: Island Level when weakened, Country Level in his Prime or with the Susanoo | Country Level

Range: Several Kilometers normally (Can affect things in his visual range), Higher with some techniques like the Susanoo

Speed: FTL Reaction/Attack Speed. FTL Movement Speed in his Prime, Sub-Relativistic Movement Speed when Weakened. | FTL

Durability: Island Level when weakened, Country Level in his Prime or with the Susanoo | Country Level

Stamina: Superhuman in his Prime, though diminished when he was sick | Superhuman, possibly Infinite (Edo Tenseis are said to have infinite chakra, though this is seemingly contradicted later)

Intelligence: Upper Genius Level General Intelligence (Regularly demonstrates incredible feats of intelligence in numerous categories), Low A Tier Combat Skill (Scales to superhuman combat skill, briefly matched KCM Naruto in Taijutsu)

Key: Alive | Edo Tensei

So if Itachi was given missions to assassinate targets in other universes, how would he do?

Kishomoto's main artistic inspiration in the writing of Naruto was the world of Dragon Ball, so how would Itachi do in the Dragon Ball World. In raw power regardless of the form of Itachi he doesn't do that well with Max Power Roshi in original Roshi able to destroy the Moon, and even suppresses with a power level of 120 able to vaporize Mt Fry by accidently with the Akatsuki arguably around this suppressed Roshi in terms of attack potency. In terms of speed if you don't think the arguments for early Dragon Ball being lightspeed apply from how Goku had to improve to reach lightning speed nearer to the end of Dragon Ball, with them only clearly reaching the FTL range in the Saiyan Saga, particularly with the Sharingan's Precog allowing users to fight people notably faster then them. 

While Itachi has some good defenses in the Yata Mirror and the Edo Tensei regen there the capacity to protect from the planetary+ ki attacks get increasingly questionable, as such for the most part Itachi vs DBZ characters really just depends on if he is able to make eye contact before they blow him up. This would actually work on at least some characters who are prone to speaking or boasting before combat though obviously at some point Itachi is too slow for them to wait for him to react. Something like Tsukuyomi could probably still incapacitate characters from Dragon Ball Z and he could then seal them with the Totsuka blade or fry their brain. He could also protect at least temporarily from dying with the Izanagi though this would be a very temporary defense if he was severely physically overpowered.

For the most part Itachi has the speed of a Saiyan Saga characters and could defeat most characters in the single digit thousands of power level via hax despite his relatively low attack potency, or possibly characters much stronger if they allow him to make eye contact, but could quickly get overwhelmed by DBZ's speed increases or by numerous characters fighting him at once. 

Bleach is one of the original Big 3 with Naruto compared to it all the time both in powerscaling and otherwise. However Bleach's scaling is definitely one of the most contested in terms of Shonen verse scaling. Generally speaking though in terms of Soul Society ranking I think it's mostly consistent for Itachi to be considered Lieutenant Rank when he's sick, and Captain Rank in his Prime. Being an Edo wouldn't particularly help since everyone in Bleach is a Shinigami or something similar that hits soul but in terms of general capacity. The Lieutenants in Bleach have feats of light-timing albeit with difficulty and from some distance, which is fairly reasonable to compare with Itachi being able to react to Kirin a lightspeed attack from a similar distance while dying in his fight with Sasuke and to feats of Early Soul Society Arc Ichigo and friends blocking a shot from a cannon that shook the entire soul society, and early Toshiro creating a storm casually with his attack that extends over a while space calced also into the gigatons range, similar to the casual feats of the Biju the Akatsuki have to apprehend. Itachi should be able to keep up in speed with Captain Tier characters that are an order of magnitude faster in the FTL range arguably even when sick via the Sharingan and definitely when he was in his prime.  Their power unless lowballed probably does start to eclipse him as the Captains are around Soul Society Ichigo's level who blocked the Sokyoku execution blade that is stated to have the power of 1,000,000 Zanpakutos while Itachi is more like thousands of times stronger in his prime by feats, and is a threat to the Soul Society itself and while Ichigo doesn't scale fully to it, he does scale to a portion of it which even just talking about the planet, would be more akin to the level of the full Ninetails.

With that said however Itachi should still be a threat to Espada and Captain Tier characters in his Prime or in Edo as he has relative speed, possibly somewhat relative power and broken hax, though he'd have a lot of interesting interactions with the verse. His Totsuka Blade is a Spiritual Weapon much like Zanpakuto and it's likely the two could parry each other. He has numerous forms of Genjutsu that should likely work though many characters in Bleach use sentient weapons such as the Zanpakutos that can potentially snap them out of a regular Genjutsu similar to how Ninja Teams break each other out of Genjutsu in Naruto. On the other hand characters in this tier can probably have their attacks blocked by their Yata Mirror meaning in a one v one Itachi can block attacks from Captain and Espada Tier threats.

Itachi's strongest Genjutsu are possible win cons though it depends on if his opponent is more like Ichigo, Grimmjow, and Byakuya, who are melee fighters who are prone to getting close and making eye contact or ranged fighters like Stark or Uryu who would just shoot at Itachi from a distance which he'd have to use the Yata Mirror to block. Itachi broadly has a very strong arsenal of abilities compared to most of the fighters in Bleach having a wide arsenal of broken techniques however he also has more weaknesses as much of his techniques have drawbacks and he has a basically normal human body and mind that is being amped such that things like being worn down and exhausted by spiritual pressure or his opponents regularly being able to fly around and even teleport through dimensions being things Itachi is somewhat limited against. Overall he does pretty well, better then most Naruto characters due to his fighting style but is far from OP. A possible Nightmare Match for him is Espada 2 Barragan who regularly leaks an aging aura around him that would probably decay the chakra flow Itachi would use to try to cast Genjutsu and even if Itachi summoned Amaterasu on his position, the flames last for 7 days and nights while Barragan believes he could decay even the stars with a lifespan of billions of years instantly so Itachi may lack a win con entirely.  

What about in One Piece, the other of the ol Big 3? In terms of power, Franky was able to withstand a mountain dwarfing explosion. Not only was this calced into the gigatons range but is visually comparable to Sasuke's destruction of the Uchiha Hideout across a mountain with this Dying Itachi being stronger then Sasuke at the time. This is consistent with a few higher gigaton level feats early into the timeskip of Elizabello and Chinjao fragmenting the arm of a massive stone golem Pica, with Chinjao at the time being around the strength of Second Gear Luffy. This means in power even when weakened from sickness Itachi should reach around the level of the Vice-Admirals and could contend with the most of the Warlords. His Prime would be more around the level of Timeskip Zoro and Gear Four Luffy who were able to slice Pica in half entirely showing a substantial increase in power calced as teraton level. In terms of speed a lot of the One Piece cast have relativistic to FTL reaction speeds similar to Itachi though in terms of movement speeds Kizaru's ability to move at lightspeed is considered a massive speed cliff for the verse with Luffy only recently eclipsing him with Gear Five, meaning that while there are numerous characters Itachi can't blitz, he can easily react to pretty much anyone in the verse and in his Prime would have movement speed comparable to the top tiers. 

Itachi has a lot of advantages when fighting One Piece characters. Devil Fruit Users are elemental enemies but Itachi's powerset broadly doesn't care about it with Amaterasu able to burn anything in Heraven and Earth, the Totsuka Blade being a sealing spiritual plane sword, and Genjutsu being mental techniques. Furthermore Devil Fruit Users are weak to water with even a bath depowering them and one of the Elemental Releases Itachi knows happens to be Water Release and with the Genjutsu's ability to read memories, Itachi can find out about this fairly quickly. Observation Haki's ability to sense presences and see the future is similar to the sensory abilities of the Sharingan while Itachi has the Mangekyo Sharingan, equivalent to the sensory abilities of Mastered Observation Haki and Conqueror's Haki which allows the mentally overwhelming someone of a weak will is going to do nothing to Itachi who had a strong willpower even as a boy and can easily reverse most Genjutsu tried to be used against him. With the ability to one-shot anyone in the verse and top tier speed Itachi would be an immense threat one v one against anyone in the tier, even characters with raw power much higher then him like the Admirals who scale to Whitebeard threatening the One Piece world.

That said One Piece does have a few advantages against him. Armament Haki allows the attacking of internal organs which is treated as a super strong ability in Naruto, bypassing most directs form of offense, and could be argued to perhaps be able to get past the Susanoo armor. This means Itachi would could be OP but a bit glass cannon-y. Also characters tend to travel in large groups meaning it's possible to wear down sick Itachi. An interesting match might be Itachi vs the Strawhats early to mid post-timeksip as they'd have numerous fighters that can physically pressure Itachi but would have never gone against someone with such a broad and potent suite of hax. 

My Hero Academia is one of the new Gen Shonen that got most compared to Naruto so how would Itachi if placed in the My Hero Academia world? Even when weakened, Itachi would be one of the most powerful capes in the setting in raw stats, as even when dying Itachi's raw power was still in the range of the Biju who would have a large amount of the power of Stars and Stripes' two gigaton level calcs of splitting the sky with Itachi and his speed is able to react to lightspeed attacks akin to some of the fastest things in the verse. In his Prime or as an Edo Itachi would be an endgame threat. While his power does get eclipsed by the top tiers like Deku's Final Smash reaching double digit teratons from changing the weather across the planet, his power with Susanoo or in his Prime would be up there. Itachi in his Prime also has arguably better FTL scaling then anyone in my Hero meaning that Itachi would be an absolute top tier physically, probably on the level of Modern Day All-Might, someone most Heroes consider the pinnacle of power.

This is a problem as Itachi has a vastly wider arsenal of broken abilities then almost anyone in my Hero save perhaps for Shigaraki. Physical powerhouses like Deku or Bakugo should be able to break through Susanoo pretty easily as Tsunade was able to break through Madara's,and while this does mean they'd have to get close enough for Itachi to trap them in a Genjutsu can fight off mental attacks shown by Deku's fight with Nighthide and the two Symbols of evil. Itachi's more advantaced Genjutsu however would pose a threat as would the Totsuka blade's sealing. It would be much safer for them to engage Itachi with a team which would likely go much better. If it's Edo Itachi they'd also need a way to kill him though All-Might was able to fight an enemy of pure energy which might allow him to hit Itachi's chakra directly, or they could rely on help from someone like Eraser Head who if you use verse equalization might be able to negate the Sharigan altogether as it is a genetic ability of the Uchiha clan. 

However more likely is Itachi fighting the villains and most villains at least one by one would not be a threat even to a Sick Itachi. Against Prime Itachi it would take likely a team to beat him though Overhaul would be a valuable asset if he can suck Itachi's chakra level (though Kisame can do this as well and admits inferiority to his team mate Itachi so Overhaul probably can't 1 v 1.) The only villains I think could beat Prime Itachi 1v1 are the the two Symbols of Evil All for One and Shigaraki, and even then it's arguable. Neither of them have the mind hax resistance to protect against Tsukuyomi and while the Rewind quirk would undo Genjutsu by reversing their body to before Itachi's chakra entered their mind, teh point of Tsukuyomi is the effect happens in an instant and fries the mind through mental trauma. Similar they lack the sealing resistance to deal with being hit by the Totsuka Blade. That said the Decay Quirk can probably eat through the Susanoo like Mei did with her Vapor Style Jutsu and they have enough raw power to just overwhelm him. I think Itachi would have a decent chance against either of them. 

Finally outside of anime, Star Wars is a verse that's had numerous comparisons with Naruto due to some odd parallels, so how well would Itachi do if he entered the Star Wars Galaxy. This depends on both canon and Itachi's status. In the Disney Canon most High Tiers Force Users scale to the feat of Knights in the High Republic being able to stop Hyperspace Emergencies that can destroy Moons or highly damage their surface, these events varying from high end city level to outright moon level with continental being most common. Itachi doesn't quite reach that high so would be more akin in power to upper mid tier force users, such as A New Hope Luke Skywalker and who's power would be notable but not a serious threat to the major force users of the OT like Darth Vader and Obi-Wan. In the Legends Canon where planet level power or higher is common among the Jedi, Itachi even in his prime and with a very high end interpretation is probably not getting anywhere substantial on raw power. In terms of speed however, most of the verse in both canons scale from laser-timing, with Legends Canon having high upscaling from it. Itachi would be able to compete in speed quite handedly in the Disney Canon and if it was Prime or Edo Itachi he might actually be notably fast compared to most characters. In the Legends Canon where there is higher upscaling with even mundane warriors able to light-time and the strongest characters scaling to massively faster then light, Itachi would have a more normal Jedi/Sith speed.

Of course the real reason to put Itachi in the Star Wars universe is that Itachi is one of the famous psychics in Naruto and Star Wars is one of the most famous psychic-verses in fiction so it's really a matter how their psychic powers compare. Both have mind manipulation, illusions, and paralysis as well as the ability to resist and the ability to enhance their reactions. A Force User has the advantage of better sensory abilities, the ability to erase memories as opposed to just reading them like both can do, and more helpfully telekinesis which would be especially helpful as it could affect him through the Susanoo. On the other hand Itachi would have high tier fear manipulation on the level of a powerful Sith, more reliable precog, sleep manipulation, and can copy techniques. He can also induce pain though for a Dark Side User that would make them stronger. This isn't getting into his more esoteric abilities like reality-warping and fate manipulation. All this is to say that I think if Itachi fought a Sith like Darth Maul in Disney Canon, Maul would be able to sense him pretty easily, but Itachi would have a high degree of speed and skill along with mind, an combined with ways to one-shot him, I think Itachi would do quite well especially as an Edo where he not only might have a power advantage but also a regenerating body where a lightsaber slash of telekinetic crush wouldn't do any permenant damage. The hard stopping part is Darth Vader who he can't use any Genjutsu except Ephemeral on because of Vader's visor that prevents eye sight. He could still try to use the Totsuka Blade but Vader can just telekinetically throw him back and unless he'd an Edo, crush him telekinetically. If Itachi is an Edo it would be a lot harder for the Disney Canon to do anything permenenant to him as he has the will and Sharingan to resist mind manipulation and his body regenerates from complete destruction though in the comics they've shown the ability to affect ghosts with the force so they may be able to hit his soul afterwards. Overall he'd be a very high tier threat, with a modest power level but good speed and top tier abilities mostly from being esoteric and unlike what people can counter. It's very likely he could defeat someone powerful but with psychological weaknesses like Kylo Ren through manipulating them with Genjutsu while setting them up to be sealed by the Totsuka Blade, hit with Amaterasu to burn them to death eventually, or get eye contact to put them in Tsukuyomi. This is especially because Jedi and Sith usually travel in pairs or by themselves, which means they really can't take much advantage of Itachi's primary weakness. 

In the Legends Canon it's a lot worse for him, his stats being relatively low tier held up by decent speed and that canon having way more abilities to scale including all of Itachi's normal abilities. Itachi's stronger Genjutsu would still be a threat though he would be only roughly middle of the road in terms of threats, being a threat to a Force User if they make eye contact and he uses Tsukuyomi though given their danger sense it's likely they would know not and they absolutely don't need to use their eyes to fight him given that they primarily fight via Force Sensing. Against powerful mundane warriors like General Grievous Itachi probably couldn't rely on his Genjutsu considering he exists in a world of Powerful Psychics though it might take him a sec to get through the Susanoo armor and if Itachi is an Edo he might have trouble killing him at all and Itachi can still try and seal him with the Totsuka blade, a spiritual plane sword he probably can't block. That said he'd probably really struggle to fight Mid Tier and up Force Users especially Dark Side ones that can often drain energy from Living Itachi's rather finite pool of it.