I think at this point Luffy might be able to give Kaido a high diff fight (at least his base form). In their first encounter, Luffy was so heated that he probably didn't even use FS. In the second fight, Luffy will make much more use of it, being able to evade much more blows. While at the same time he will be able to eat more blows too (he always comes back stronger against the opponent he lost before). Now comes his advanced form of CoA which is even more powerful than what Hyogoro displayed. This combined with the ability to use G4 more casually and fire KKGs instead of KGs repeatedly, I think that will give Kaido some challenge.