Kaido’s stamina being low doesn’t affect his damage output. He has yet to be severely damaged, no attacks so far indicates he was affected greatly. Scabbards, and Yamato gave him virtually 0 damage, he would have regen’d those hickeys by now with his mythical Zoan. Doffy getting hit by a gamma knife is a bigger nerf if you think about it.
Luffy’s yonko level because he can now stand his ground damage-wise against a yonko. EOW Luffy’s definitely yonko level believe it or not, but I can see when you think Kaido’s still stronger. This is the same argument on WCI, when people were saying Luffy’s not YC1 level after Kat nerfed himself. 😒