I think most have been stated already.
There's one thing he truly lacks and that's mobility. He's obviously fast af. He was on his way to stop hakai while the other were still standing. Plus King obviously. But he needs those super jumps mihawk and shanks can pull. He needs something better to fly (moonwalk). No idea why he didn't pull a Soru until now. Cause obviously he's far superior to people using it (for example Kaku, even pre ts).
Regarding asura:
It's still not clear if asura is a CoC related attack or if kaido just sensed CoC while tanking it. If the first statement turns out valid, there's nothing stopping zoro from pulling a haki susanoo. Maybe shanks does it first and confirms it. I'd also imagine an asura transformation that stays for an extended period of time, kinda like luffy's gears. Because why shouldn't it be possible.
If no, he could at least use asura with Adv CoC but that's nothing really new.