Kaido was wasted, in the opposite way of how Big Mom was wasted by Oda, with him getting so little personality development, so little backstory and so little interactions and dynamics with his own crewmates.
Sad part is there is implied to be so much history been Kaido and King.
King was his first crewmate and started the BP together.
King influenced him so much that it's implied Kaido thought he was Joyboy himself at some point, and then later came to think he wasn't anymore (how this shift in perspective happened is another abandoned plot point).
King only shows his face when alone with Kaido.
During both their defeats, they saw each other in flashbacks.
There is so much implied, but nothing shown on screen.
The entire thing was ridiculously rushed, while Loda wasted time on a lot of nonsense (which also got abandoned/ went nowhere eventually).
Feels like Oda wanted to do much more than what was written, but scraped them for whatever reason. Worse, he rushed or abandoned the most important aspects.
Retarded writing.
IMO Wano would've been a masterpiece if it went on till 1100 chapters, with all/most plot points and character moments being addressed, or having some form of closure.
Instead we got dogshit surpassed only be Egghead.