YALL HEAR ME OUT
Kaido acknowledges Yamato's strength.. and him telling flying 6 to bring her for them to have a chance against the calamities, so basically Kaido meant that someone capable enough to bring a restricted Yamato would prove one's eligibility to fight a Calamity .. and restricted Yamato was seen casually clashing with ulti and even knocking her out for
minutes.. with her restricted strength... and she was able to keep up with base pissed luffy and gear 3 moves while on defence which luffy just showed to nearly loosed Pay Pay's jaw (ancient zoan)
So if beating a nerfed Yamato (who was able to do all that in her restricted state) would grants them a fight with a Calamity..which logically be more arduous than beating a restricted Yamato.. and considering the fact that a F6 would rather choose jack as an opponent over King or Queen for better chances and seeing how WW smirked when Jack was the one who said "no probs kaido"
Then theoretically Yamato (not restricted) would beat the strongest flying 6 unrestricted without her DF but with her DF she scales above Jack considering how Sulong Neko and Inu did against Jack and Kaido acknowledges jacks strength to but puts the Minks Sulong above jack.
The reason why I'm stating this is coz.. if Yamato by any stretch of reality is on Queen's level..
then with that logic sanji would be doing as well as she is atm with Kaido.... or better as sanji shall beat queen... atm as things stand i believe jimbe can whoop Jack as well so... Yamato may possibly be over him as well.. and near around Sanji's stakes... depending on how sanji does thing...whether High diff or extreme the gap between Yamato and Sanji would increase and decrease accordingly.
Just common comparison, sanji doesn't need to fight a Yonko 1v1 to scale his strength.. i believe kaido is just stalling Yamato.. he isn't "Worked up" like hd was fighting a nerfed luffy.. so Zoro should theoretically do better than sanji and Yamato.. all out against kaido.