This has already been discussed, but…
Akainu is probably blood or lava based. Lava would make more sense. Here's why:
1. A marine admiral has to be mobile. Therefore, some kind of extraordinary travel method is needed. What happens when lava hits seawater? It cools and creates magma. hardened magma is the base support for 90% of the world's islands. He could simply create magma roads wherever he goes, and use something similar to the bike Kuzan uses.
2. A marine admiral must be strong: The ability to weild 2000 degree lava? Yeah, that's pretty damn tough to beat.
3. He wears a hood and a hat over his eyes. Flash from lava flames has been known to cause blindness if you look directly into them. A hat and hood would really help.
4. An admiral must be good at covering things up. Therefore, he could let nature do it's course. Lava destroys all vegetation and animal/human life when it comes in contact, then it hardens and turns to magma. Everything becomes soot and ash. Gone. Perfect method.
As for Kizeru... I wanna say his power is a Goku Goku no Mi, Model: Spider Monkey. He could be really fast and kick ass while in his spider monkey form. And possibly have something similar to rumble balls.