Kaidou knows how to fly
And if he wants support, he just needs to break a piece of rock and make it float with his flaming flames and use it as a base.
Hitting Kaidou with water attacks won't do anything to him, he needs to be submerged up to his neck in it for it to have any effect, and he will only be weakened if he is, but he will still be able to move.
Not to mention that Kaidou can use the heat breath to cancel out all that water when Kizame is about to shoot.
And also the water comes out of Kisame's mouth well, and Kaidou comes out shitting lightning bolts with every attack he has, it won't electrocute the fish?