Crocodile Chef is good. Has a cleaver, that is good. For his gun I maybe would rather see him spew flies from his mouth.
Splash has interesting effects. My criticism though is I don't like seeing it stand alone as a passive without being on an ability. There's not a precedent for that in game. I think it needs to be a passive with explicit rules. Applies to melee attacks. Applies to ability damage, etc.
I like the idea of a swarm of piranhas. The way I would do this one is to have the swarm only move when the Crocodile guy hits something with a melee attack or maybe another ability, otherwise they stay in place. Adds character to the spell, I think.
Pressure Cooker is good. Kind of silly, but good ability. It works. Deep Dive is too complicated. We have a character that does Burrow Strike. Maybe Crocodile Guy needs to ride in a wave instead.