If you guys remember, Gecko Moria claimed to have fought Kaidou himself in the past, so I assumed he must've gone to the New World. However I think that might not be the case at all. I think Moria fought Kaidou near the Thriller Bark Ship.
Near the end of Thriller Bark, Lola and her crew took Brooke's old ship to sea, but then...
They encountered this entity larger than Thriller Bark which is known to be the largest pirate ship in the world, yet this entity completely dwarfed the ship. So these could possibly be the strongest creatures in the one piece world.
Oda has to explain what these creatures are so he may in the future link them to Kaidou since he's known to be the strongest creature in the world so could it be possible that Kaidou is one of these things and if so could he have eaten a human-human devil fruit with a different model from Chopper's that gave him a human like appearance.
Another theory is that Kaidou ate a mythical zoan devil fruit model: Typhon
Typhon is known to be the strongest creature in legend greek mythology which would further support Kaidou's feat of being the strongest creature in the One Piece world, but also Typhon is known to have 100 dragon heads replacing his head or arms or legs which can be definitely be linked to the whole Kaidou and the 100 artificial devil fruit army.
So what do you guys think of these theories and what are yours?
Epic!!!! He would have a unique devil fruit in which he is actually water tolerant!
Kaidou of the beasts either means he himself is a Zoan user or he simply commands Zoan users.....based on what we just learned, Kaidou owns Zoan users, bur I'm betting he is also a Zoan user. My guess would be an ancient Zoan fruit....Maybee one that links him to the water as you mentioned and showed with the Thriller Bark ship.