I think "silly" fights are always warranted, or at least portions of those fights. Some of the more serious fights, being Crocodile, Lucci, Doffy and Kata were all pretty serious with some funny aspects added at certain points (Mizu Luffy, G3 side effect, G4's initial intro, Merienda).
Kaido definitely falls under something serious but it clearly was meant to come off as entertaining for both opponents, which is very different from past fights.
Imo, this kind of trend will at least continue with Blackbeard. There's something insanely wacky with his powers that I feel have to be addressed in a ridiculous way with Luffy. Maybe Im falls under this category depending on their relative strength or temperament
With Akainu and potentially Shanks, I think we are geared more towards serious battles because lf the nature of their powers. There's really nothing fantastical about a magma user who can kill you in one hit or a blade user with no external powers save for haki mastery (and potentially to a degree we don't know), so imo these will be more serious fight.
Basically:
- BB (and maybe Im) will probably fall under the more crazy or bombastic type fights which Enel, Moria, Magellan, Caesar, and now Kaido have sort of fallen into. The more "epic" feeling fights becuase of the nature of BB's powers and how Luffy will counter them.
- Akainu/Shanks would probably feel more like Lucci, Doffy or Kata. More hand to hand, punchy, haki displays where techniques are more based straight up on how much you are trying to kill the opponent (i.e. melt them or cut them up). They'll still have their stupid moments though