How they compare: Yami/Akuro (Okami)

Yami is the final antagonist of Okami. Yami is the Emperor of the Demons and long ago stowed away on the Ark of Yamato, before sending his champion Orochi to attack the celestial plane of high heaven, causing the celestials there to flee to Earth on the Ark of Yamato, bringing Yami and his demonic legion, as wanted, down to Earth. 

Okamiden reveals Yami was the body possessed by the spirit of pure darkness and embodiment of all that is evil, Akuro. Yami, unlike the other demons who seek power or to casuse chaos seeks nothing less then the destruction of all things, plunging the universe into darkness. 

Yami is one of the strongest beings in Okami, stronger then any being really save for the full power of Amasterasu. Even her she can compete against well.

Yami is powerful enough that even his disembodied spirit Akuro can create his own dimension filled with stars. In his proper body, Yami's strikes against Amatearsu creates shockwaves that could destroy the constellations, the sizes of which would be small galaxies, purely as a side effect. Amaterrasu even midgame with her brush power could spin the whirlpool galaxy at massively faster then light speeds meaning Yami would be galaxy level in terms of attack potency and durability.

In terms of speed, Amaterasu's wind traveled to the whirlpool galaxy at 69 trillion times the speed of light and she is easily comparable to this speed mid-game. This would mean that Yami should be well above 69 trillion times the speed of light.

Yami's seeming metalic form is adjustable and he in fact possess 5 forms, each stronger then list though most look fairly similar. His spirit Akuro while weaker was also a spiritual entity and as such would not be harmed by purely physical attacks.

Yami possess numerous powers and abilities. His form can be adjusted to create hammers, missiles and lasers or giant hands. As Akuro he displayed the ability to project fire, ice and lightning from his mouth. It is also completely ageless, existing for countless centuries and  resists time manipulation as Amaterasu's time stop did not work on Yami. Yami can naturally levitate and survive in space.

Perhaps Yami's most broken ability is his power absorption. Yami stole the powers of the celestial brush from Amateras rendering her powerless. During that period it's likely he could use the same brush powers Amaterasu could. Yami is also stated to be able to cause an eclipse that can dramatically strength himself, though he can only do this once per century. It's also noted that all forces of evil naturally obey Yami, though it is unknown if that is just out of respect for him as their emperor, due to his raw power, or due to an actual form of mental manipulation on evil.

Akuro demonstrates more abilities including dark energy projection, manipulation darkness as the embodiment of all darkness, and a form of regeneration/absorption as his spirit was divided into 5 pieces, and over Okamiden is finding the other pieces to reabsorb back into himself. This relates to his other powerful ability; his possession. When Yami was defeated, Akuro was split into 5 pieces which found each a different vessel and possessed them with the primary piece seeking to reunite them. Though it is stated that only the proper vessel for himself, would be a vessel of light bathed in the blood of Orochi.

As Akuro he was actually quite manipulative howeve he possesses a particular resistance to manipulation. Yami is noted to be an eldritch entity and it is said that unlike every other being in the game he can not be presented as either an animal or a human because his nature is so differnet all organic things. This means it would likely be harder to manipulate or even predict the actions of Yami.

Yami has 2 weakness, both somewhat unconventional. The first is that the Holy Light of the Sun, the power of the Great August Kami who shines in Heaven (Amaterasu) weakens him severely, for he is of the dark. Secondly his body seems to be something akin to metal and magnetism works so severely on him that even Akuro his spirit is affected by magnetism.

Note: Yami and Akuro can be viewed as two seperate characters or as one character. Yami is a vessel and Akuro is the spirit possessing the vessel though he views Yami's will as his own so he clearly views himself as one entity. There is literally no information about Yami without Akuro, if such even exists outside a very debatable interpretation of Yami's final appearence. As such I mentally classify them as one entity or at the very least the two can fight as one entity.

Name: Yami, Akuro, Tokoyami -no-Sumeragi

Origin: Okami

Classification: Emperor of Everlasting Darkness

Powers and Abilities: Superhuman Physical Characteristics, Sheapshifting, Weapon Creation, Elemental Projection (Fire, Ice, Lightning, more with Amaterasu's powers), once a century can create an eclipse to empower himself, levitation, ageness, can survive in space, power absorption, dark energy projection, darkness manipulation, dimension creation/reality-warping (Akuro created his own dimension filled with stars), spirit can act independently if body dies and can regen from being split into 5 pieces as well as possess entities, possible control over evil entities, resistance to time manipulation, more powers with Amaterasu's powers

Weakness: The Holy Light of the Sun, Magnetic Manipulation

Destructive Capacity: Galaxy Level+

Range: Likely Inter-Galactic (Destroyed multiple constellations with the shockwaves of his strikes)

Speed: MFTL+ (Trillions+)

Durability: Galaxy Level+

Stamina: Unknown, possibly infinite as Yami is a spirit possessing a mechanical vessel

Standard Equipment: His own body which can shapeshift into numerous weapons

Intelligence: Manipulative and Cunning

So how would he do in other verses

In Marvel Comics, Yami would be classified as a Low Skyfather Tier entity. Fighting against a Herald he would have a large power advantage since they would at most be relative to midgame Amaterasu, though depending on which one they may be able to hax him, as he is likely only somewhat relative to speed. That said in terms of raw power he can one-shot especially given his ability to absorb their powers which would make him even more dangerous. Against most Skyfathers outside the stronger ones, he should be a relative threat, maybe a bit on the slow and non versatile side though he has the advantage of being able to rapidly grow stronger and power steal which would be quite stronger. He would be comfortably outclassed against any Cube Level Being so Yami fits very firmly in the Skyfather tier. 

In the DCU, Yami would struggle against most heavy duty speedsters but against anyone who can't blitz him he would be a massive threat due again primarily to his power absorption and ability to rapidly grow stronger. In terms of raw power he would be above most post-crisis powerhouses and would be a relevant threat even in the pre-crisis days, being even stronger then Sun-Eaters who can consume entire galaxies. He would not be quite as strong however as Pre-Crisis New God Emanations like Magnar who hits with the magnetic force of a hundred galaxies, which would be particularly effective against Yami due to his spirit being prone to magnetism. Yami would be a drastic threat in the post-crisis era, requiring likely several power JLA members to stop  and would be a mid-tier in the Pre-Crisis era with not insignifigant power and a very strong ability but not very fast.

In the Darkstalkers Universe, Yami would be....an interesting threat. Yami would be a powerhouse in raw stats certainly as while the verse does have feats of billions to trillions of times lightspeed and galaxy level power (Huitzil traveling to Earth quickly and Pyron having an orbital path twice that of the milky way)  the later of these is seen as a feat of ones of the strongest characters and the maximum power while Yami is well above the baseline. Similarly Jedah Dohma was able to reach galaxy level via his reality warping though agian Yami should be stronger in raw power. Yami also actually possesses a way to get past Jedah's incredible level of regeneration, that being by stealing his regeneration. That said, via intelligence, versatility or numbers, the verse does have ways of beating Yami. In particular Jedah likely could seal Yami away via dimensional bfr as Yami was unable to travel to the mortal world of his own accord and required the ark of yamato to bring him between worlds. Overall Yami would likely be a high tier fighter in the verse, but not an insurmoutable threat.

In the Bastard!!-verse Yami would probably not do very well to be perfectly honest. In terms of raw power he is comparable to the likes of Dark Knight Lucifer Dark Schneider and Fallen Uriel's powered up form as the two were both capable of destroying galaxies before powering up by 170 times twice each. Yami may have a speed advantage as their highest speed feat would be in the million of times lightspeed range (DS and Uriel's clash traversing the diameter of the black abyss each time they struck) though they are vastly stronger then they were. That said Yami would have a signifigant difficulty in harming any entity with Eternal Atoms unless he could absorb their powers which would be unlikely since he would have to get through dispel bounds. Yami would have to kill a weaker angel/demon and work his way up though even then he would likely be a versatiltiy disadvantage. His own spirit would not be safe at all since not only do the Seraphs have powerful holy lights but they also all have attacks that can ATOMIZE the body, soul and spirit which would kill Yami.

In the Sailor Moon verse, Yami would likely be above Pharaoh 90 who moved a galaxy at mftl speeds which is an almost identical feat to Amaterasu's mid-game feat and Super Sailor Moon's whose intitial henshin was over 10,000 times that of Pharaoh 90's power. His power absorption would be an exotic ability to the verse nad he could be very dangerous though he would have to be careful against a bearer of the Silver Crystal as they can use the holy light of the crystal which should work on him the same as Amaterasu's light. He'd ovewrall be very similar to a Chaos Star, an eldritch powerful and hax cosmic entity that seeks to bring about oblivion who can defeat most people via hax, even the ones stronger then them, but would lose to the Silver Crystal.