Akainu is a front-row character, his primary attribute is strength and his basic attacks are physical
Vivre cards
Apart from various "Achievements" and "Tasks", Akainu's Vivre Cards like any admiral is only available in the Bink's Sake, a VIP 11 feature in the tavern. This is currently the only way to obtain him until further updates (most likely future chapter 12 that might contains the Marine HQ fights). He costs 80 vivre cards, so he starts with 3 stars.
Skills
Meteor Volcano(special skill)
Physical or elemental: elemental.
Range: one way, all enemies within first 5 meters.
Stun: none.
Damage amplification: unknown.
Other info: none.
Great Eruption(second skill)
Physical or elemental: physical.
Range: one way, all enemies within first 1 meters.
Stun: none.
Damage amplification: unknown.
Other info: none.
Hound Blaze(third skill)
Physical or elemental: physical.
Range: closest, single enemy.
Stun: none.
Damage amplification: unknown.
Other info: none.
Magma Transformation(passive skill)
Effect: Increase own defence against elemental attacks.
Other info: none.
Equipment
Equipment level 1 (White frame):
Hawking's Cards, Hawking's Cards, Sword, Sword, Battle Axe, Iron Armor
Equipment level 2 (Green frame):
Equipment level 3 (Green+1 frame):
Equipment level 4 (Blue frame):
Equipment level 5 (Blue+1 frame):
Equipment level 6 (Blue+2 frame):
Justice Overcoat, Shusui, Kukri, Kukri, Pearl Necklace, Morgan's Teeth
Equipment level 7 (Purple frame):
Kogarashi, Lassoo, Cross Sunglasses, Mihawk's Cross Pendant, Golden Pistol, Magic Wings
Equipment level 8 (Purple+1 frame)(unsorted):
Ace's Hat, Enel's Staff
Equipment level 9 (Purple+2 frame)(unsorted):
Kinemon's Sword
Equipment level 10 (Purple+3 frame)(unsorted):
Kid's Goggles, Law's Hat