Kuzan (more popularly known as Aokiji) was a former member of the World Government in the One Piece universe. His devil fruit was extremely powerful and could create bridges across (or outright freeze) entire oceans on a whim.
With enough power to rise to the rank of admiral, there are few characters who can rival Aokiji's frigid might. Through identifying the characters able to challenge him and those who can't, we can better assess how strong Aokiji really was and why he was one of the first to defeat Monkey D. Luffy.
10 Rivals Aokiji: Kizaru Dominated The Worst Generation & Nearly Destroyed The Straw Hat Pirates
Kizaru's logia fruit works much like Aokiji's own. It necessitates that only armament haki can injure him and also provides other benefits like instant teleportation and no elemental counter.
The admiral had a chance to prove himself by obliterating the Worst Generation during his unannounced visit to Sabaody. Were it not for Kuma's unlikely betrayal, Kizaru would have been able to kill (or at least capture) the Straw Hat pirates. This was a feat that Aokiji matched before Luffy's visit to Water Seven.
9 Nowhere Close: Nico Robin Still Has Yet To Pose A Threat Against Aokiji
During their first encounter, Aokiji decisively defeated Nico Robin despite the allies she recently made. Although Robin has become considerably stronger since the time skip (proving able to sustain her winged form and even create gigantic feet), she still suffers from the same fundamental problems in battle.
Not only do her extendable limbs reflect damage back to her (making melee attacks ill-advised), she hasn't mastered armament haki like Luffy or Zoro. Consequently, she would have no conceivable way of breaching Aokiji's logia defenses.
8 Rivals Aokiji: Doflamingo Respects What Aokiji Can Do
After Luffy left Punk Hazard with Caesar Clown, Doflamingo personally arrived to interrogate Smoker about his whereabouts. Since the marine wasn't willing to betray his one-time ally, the villain prepared to murder him.
However, Aokiji intervened and stated that if the Warlord intended to continue with his plan, there'd be a second fight on his hands. Since Doflamingo relented, it can be assumed that Aokiji's power is at least equivalent to (if not greater than) his own. This is especially true since Aokiji was no longer a member of the World Government at the time, so there wouldn't be any political fallout for his potential death.
7 Nowhere Close: Aokiji Counters Crocodile's Devil Fruit Brilliantly
Having stood up to Akainu during the battle for Marineford, Crocodile is a formidable warlord. However, he was still defeated by Luffy early into his career as the Straw Hat captain and before he came upon Aokiji. This illustrates a clear disparity between Crocodile's skill and Aokiji's.
The divide is furthered when considering Crocodile's weakness to water. Since Aokiji can create copious amounts of ice on a moment's notice, he could petrify the Warlord before he had a chance to disperse himself and escape.
6 Rivals Aokiji: Rayleigh Proved That He Could Fight Admirals At Sabaody
As the first mate of Roger himself, Rayleigh's age has not significantly inhibited his performance. During the invasion of Sabaody, he proved to be skilled enough not only to fight Kizaru evenly but also managed to keep an eye on the Straw Hats while doing so.
Considering his mastery over armament haki and significant advantage of experience, he wouldn't struggle to contend with Aokiji's logia fruit regardless of its icy and debilitating effects.
5 Nowhere Close: Hody Jones Wouldn't Be Able To Utilize Water Efficiently Against Aokiji
Hody Jones prefers to attack Devil Fruit users near an abundance of water. Not only does it increase his strength, it also portends that his opponent will drown if they aren't careful.
Even if Hody reaches his maximum potential through steroid usage, Aokiji's abilities are a natural counter against him. Should he dip a finger in the water, he could reduce Hody's swimming area into a giant cube, thereby petrifying his adversary and resulting in the fish-man's safe and expedient capture.
4 Rivals Aokiji: Marco's Devil Fruit Provides An Elemental Counter To Aokiji's Body
Marco was one of Whitebeard's most reliable sons and a prominent figurehead at the battle of Marineford. Like Rayleigh, he was able to keep up with Kizaru, an admiral faster and with more destructive potential than Aokiji.
His regenerative powers alleviate much of the pressure Aokiji could unleash through icy meteors and touch. Additionally, Marco's naturally smoldering body would make an effective elemental counter to his opponent's logia even without factoring his armament haki into the battle.
3 Nowhere Close: Aokiji Can Attack & Defeat Caesar Clown From A Safe Distance
Caesar Clown's ability to siphon the oxygen from his immediate vicinity makes him extremely deadly against melee users. When compounded with his poisonously gaseous body, both direct and ranged approaches against him are ill-advised.
However, Aokiji proved exceptionally durable when managing to survive an attack by Whitebeard. Additionally, since he can project his ice across a large radius, he would have an easier time freezing the oxygen that comprises Clown's body, poetically knocking him unconscious in a way he often attempts against his victims.
2 Rivals Aokiji: Aokiji's Fight With Akainu Tore Punk Hazard Apart
After Sengoku announced his retirement, Aokiji and Akainu both vied for the honor of becoming fleet admiral. To settle their differences, they fought on Punk Hazard in a battle that would shape the fate of the marines, pirates, and even the World Government itself.
Although the duel lasted an extremely long time and despite Aokiji's elemental advantage, Akainu was ultimately victorious. The fight was so narrow, however, that the island they battled on was perfectly terraformed. The icy and burning sides were perfectly divided by a lake in the middle of the territory. Given this, it can be assumed that the two admirals are on a similar power level.
1 Nowhere Close: Franky Has Extremely Limited Options Against Aokiji
Preferring to rely on raw technology instead of haki or Devil Fruits, Franky's options against Aokiji are limited. His radical beam and fresh fire are the only utilities that might pose a threat to the admiral, but given the man's experience, they would be relatively easy to dodge or block with icy walls.
Unlike Franky, Aokiji demonstrated a nearly endless amount of endurance through his battle against Akainu. Considering that his opponent runs on cola, he would be well equipped to win a battle of attrition.