How they Compare: Zagato

SPOILERS FOR MAGIC KNIGHT RAYEARTH

In the land of Cephiro, will controls all. There existed in that land a woman who was entrusted to maintain peace and harmony across Cephiro. The pillar of Cephiro, known as Princess Esmeraude had to pray at all times for the good of Cephiro. Assigned to protect her was the knight Zagato. However against their wills, the two fell in love. Emeraude's heart impure and unfocused, Cephiro began to break apart, with horrific monsters and natural disasters appearing.

To protect his love, Zagato kidnapped the princess taking her away, hoping to save her and to finally bring his beloved peace. In a way, Zagato is still just doing his old duty of protecting the pillar, though motivated now by love. Zagato's will to protect Emeraude gives him his great powers, and he is willing to destroy the world if it means protecting her.

Zagato's power is vast even for his verse. He is physically strong and skilled enough to match Cephiro's greatest swordsman Lafarga. Lafarga was so strong that even at range, the pressure of his sword swing was able to create a crater in the ground calced at requiring 9.8 tons of tnt to create. Zagato's so powerful that with a mere gesture he was able to create a forcewave capable of destroying the Escudo armor of the Magic Knights, armor as tough as the Magic Knights' own will. With his Rune God, Zagato was able to match the power of the Magic Knights' Rune Gods, who were strong enough to battle a planetary reality-warper able to create a planetary scale forcefield to protect against inter-planet invasions. 

In terms of speed, Zagato scales to the Magic Knights from having a will on par with theirs until near the end of part 1, and being able to pilot/fight with Regalia at FTL speeds at close-range with the Magic Knights' Rune Gods. The Magic Knights were also able to slash a creature that was a living light and easily deflect the lightning attacks of Lightning Element Inouva. 

Zagato's stats come from his sheer will, among the greatest in Cephiro. His will was so great that he was able to create a Rune God (Mecha) for himself, capable of matching Rayearth, Celes and Windam, three rune gods, all at once, despite them being ancient and experienced. Zagato's will was so strong that the Magic Knights had to combine their wills to beat him, and they were later able to defeat a planetary-reality warper via their will, suggesting his will should be high enough to resist planetary-scale reality-warping via scaling.

Along with his will and physical capacity, Zagato is one of the greatest magic-users in all of Cephiro. He is so much so that Alcyone, rebellious student to the greatest magic-user in Cephiro Guru Clef who was able to delay him for a time, is only a subordinate of Zagato. Zagato's magic is strong enough to transmute, turning even a master mage to stone, and possibly being able to turn another powerful mage into wind. He turned the lightning element Inouva into a humanoid being, and at his request returned him to his true form. He also brainwashed Lafarga into serving him showing he can control the minds of others. 

Besides that in terms of magic Zagato can cover himself in a dark energy aura and a shield capable of blocking attacks from all 3 magic knights at once.  He also has several named magic attacks including "Shadow Impact Lexus" which fires a dark electrical orb at enemies, "Silver Death Strike Diablo" which creates a massive explosion, and "Stratos Night Explosion" which attacks with two spirals of dark energy.

In addition to being a skilled warrior and mage, Zagato is skilled at stealth and manipulation. He was stealthy enough that supposedly only Guru Clef and his magic could have detected him, and he is skilled enough at manipulation to trick others into serving his wills.

An OBD-Style Profile for Zagato:

Name: Zagato

Origin: Magic Knight Rayearth

Classification: Dark Lord, Knight, Mage

Powers and Abilities: Enhanced Stats, Superhuman Will, Creation, Matter Transmutation, Brainwashing, Forcefield Creation, Magical Aura, Elemental Projection (Electricity, Darkness), Energy Projection, Force Projection, Summoning (Rune God), Resistance to a number of haxes via will

Weakness: Nothing Notable

Destructive Capacity: Likely City Block Level in Base, Planetary with Rune God

Range: At least several kilometers

Speed: FTL Reactions in Base, FTL with Rune God

Durability: Likely City Block Level in Base, Planetary with Rune God

Lifting Strength: Unknown

Striking Strength: Class GJ in Base, Class NJ with Rune God

Stamina: Superhuman 

Standard Equipment: Armor

Intelligence: Above Average, Manipulative

So how would he do in other verses?

In DC Comics, Zagato with his Rune God would be roughly on par with the general Teen Superheroes like Superboy and Wonder Girl in the Post-Crisis on continuity due to his planet level and ftl capacity, though due to his magic and hax abilities he would likely be on the upper end of this tier. While his haxes would likely work on people above his tier, he would struggle due to power difference. His base form would be a perfectly decent streetleveler, though his hax and high reaction speed would make him relatively dangerous for one

In Marvel Comics, Zagato with his Rune God would rank roughly on the level of High Metas like The Thing and Alpha Level Mutants, though he's be more hax and a bit faster then mots of them. He would not be very likely to do well against any of even the lower herald level entities however, being weaker not just in stats and haxes.

Zagato's base form would be a dangerous threat at street level with his high reaction speed and haxes, though top tier marvel street level humans would be significantly stronger. 

In Wedding Peach, Zagato would be roughly on par with the High to Top Tiers. He would be able to have a very fair fight with any one of the Super Love Angels with one of the sacred 4. Assuming he can affect them, he could also fairly fight any of the Stronger Demons in the series. That said he would not have the versatility and have slightly lesser power then Queen Reine Devilla or Sacred 4 Wedding Peach, meaning he would be below the God Tiers. 

In the Cardcaptor Sakura series, part of the same CLAMP Multiverse technically, Zagato would place interestingly. He would be much stronger then any individual Clow Spirit due to being more raw powerful then all but 2 of them, The Light and The Dark, and so fast only the fastest, The Dash would be able to keep up. He also has powerful magic abilities and manipulation would get him far in the verse. That said the strong CCS Mages have resistance to magic eclipsing him and while he would be able to beat Part 1 Sakura, Part 2 Sakura, Eriol, or any of the Clow Guardians restored to their true forms should be able to beat him in a one on one fight, though for one of the Clow Guardians it would be fairly even. Sakura likely befriends him though.

In the Madoka-verse, Zagato would be a relative powerhouse for most of the universe (though Madoka has a rather extreme power jump). None of the "normal" magical girls have the speed to blitz base Zagato or the ability to resist his haxes, even if they have raw power on his base state. That said his Rune God state would be effectively a god tier to most of them, as it would be able to solo Ultimate Walpurgisnacht, being able to resist it's haxes and destroy it in a few attacks. That said he would obviously not be able to do anything to Kami Madoka or Akuma Homura. The Incubators would likely want to try and harness his willpower to see if it can help prevent entropy and given the degree of advanced-ness for their civilization, it's possible they could succeed.

In Sailor Moon, would be a relevant threat for the prequel in his base form and for the first arc in his Rune God Form but would eventually just get out-stated. In Codename Sailor V, he actually has reflexes to not get blitzed by anyone, and his stats would be strong if not super broken or out of the ordinary for the verse. He'd stick out like a sore thumb if the mostly silly Codename: Sailor V but statwise he would fit right in, having power about on par with a Dark Agency Member. 

His Rune God Form would be somewhere around the level of Kunzite from Sailor Moon, and so be a relevant threat for a good part of the first arc, even near the end where he would be outpowered, his hax would still be significant enough that he could be a credible threat.