Jozu is the commander of Whitebeard's 3rd division.

First Appearance: Chapter 234; Episode 151

As the commander of the 3rd division of the Whitebeard Pirates, Jozu has authority over the lower-ranking subordinates. He was one of the few men unaffected by the powerful Haki released by the Yonkou Shanks. He is very experienced and a veteran of the Whitebeard pirates from the times of Gol D. Roger.

He is one of the strongest members of the Whitebeard Pirates, as shown by his position as the 3rd division commander. During the Marineford war, Jozu was powerful enough to fight on par against the Shichibukai and the Marine Admirals.

Jozu has outstanding brute strength, comparable to that of the Giant Squad Marines. He picked up and hurled an immense iceberg at a great distance at the giants protecting Marineford. The iceberg was so enormous that it appeared to be at least ten times as big as any of the giants. Thus, Jozu has demonstrated one of the greatest strength feats seen in the series. And, despite his massive body, his speed and reflexes are on par with his brute force; when he attacked Crocodile after the latter attempted to take Whitebeard's life, Crocodile commented on both the great speed and strength of the attack.

Jozu has eaten a currently unnamed Devil Fruit that allows him to transform, parts and most likely all of his body, into diamond. This power has earned him the nickname "Diamond Jozu". It is currently unknown if this is a Paramecia, like Supa Supa no Mi.

Jozu's powers give him the ability to greatly increase his offensive and defensive powers. His already strong physical attacks are enhanced by the density of his diamond body. His defenses seem to enhance exponentially, and he is able to block the strongest slash in the world from the world's greatest swordsman, Shichibukai Juracule Mihawk, with no visible damage to himself. However, when his whole body is not in full diamond form, he is still vulnerable to Aokiji's freezing abilities. Other than that, Jozu is weak against the standard Devil Fruit weaknesses.

(Source: One Piece Wiki)