I'm pretty good at this game, and these tips helped I guess.
With Yugo at the very start of the game, when the dude says "FIGHT" slam on the grapple move and Yugo'll chew on the foe like a ragdoll. I find that funny
Turn into the mole (not the robot one)and tap down twice, until he's curled into a ball on the floor, and hit B I think, and he'll punch the ground, and if the enemy is nearby, there'll be a shockwave, and the foe will fall over numb.
As the chameleon, its supposed to be better being in hyper mode (invisible) but I think that makes it tougher, and it wastes time.