Zunisha is definitely stronger than an YC3 yeah.
It's funny how Kuzan could easily freeze him instead. With utter ease as well. Nothing stops him from performing so at least. Unless Zunisha can prove to be able to break out of ice.
Zunisha's large scale ice abilities are only effective on water, and it's only a fairly surface level degree of it, he could try to pin zunisha down with it by freezing a part of his legs to stop his movement, but Zunisha being as tall, big, and strong as he is, breaks free. We know the ice doesn't go to the bottom of the ocean (where zunisha is standing on) or even anywhere close to it cuz of marineford when the ice stopped going after law's submarine. And he can't use ice on the scale of zunisha through regular ice attacks, his regular aoe large scale attacks are scaled to ace's entei or whatever ace's ultimate was. That's a move that zunisha can easily overpower away. We're talking about old zunisha btw, prime zunisha is prob stronger than roger tbh, he's decayed asf now and has been walking for 1000's of years (or was it just 1000+? Still a lot)
Also considering Zunisha has the best kenbunshoku feats to date (Finding momo and luffy on his back, and also doing that thing that let momo see through his eyes to show him the threat of jack so he could be allowed to attack jack), it's safe to assume his busoshoku and kenbunshoku are massively up to par, if not superior to admiral/yonkou tbh. I honestly wouldn't be surprised if he had haoshoku, I'm of the belief that he was probably a rampaging figure who thought he was a god before a distant like void century or whatever ancestor of oden/momo from the kozuki line defeated him, then told him to do the punishment, which zunisha forced upon himself all these years to with-hold (probably started with a "get walking and never stop" gag that zunish was too oblivious or honorable to stop doing). But yeah, Zunisha honestly could be god tier for all we know, he's at least yonkou leveled though, the move that one hit jack was essentially a casual non buso bitch slap.
But yeah, no one is going to particularly catch zunisha off guard when he knows they are there, even if they are small, if he can resist (ie free of his punishment), so he will be able to resist stuff, and honestly, I can't see someone like aokiji surviving a single attack from a zunisha who is full like rampage mufasa death zunisha, like a full running charge, buso and all.
I want to see Zunisha fight Kaidou or Imu tbh. If I'm right about mariejois being pluton, I could see Zunisha being the reason why the allies can even get there (he might die in the process, but he's going to outright tank some pluton hits and make sure luffy and everyone gets on mariejois so they can have person on person fights and the alliance can literally pillage like pirates the holy land of mariejois.