No one is defeating either of them. That's why there is 5.Zoro looks like he be hype tool by Yonkos given we know he isn't defeating neither.
It was a face to face confrontation. Kaido sees him before he can even attack.Yeah while Kaido was focus on Luffy and he took his chance to strike at him. Not face to face confrontation. By that logic we should put Franky in this given he attack Big Mom while she wasn't looking at him, so he could harm Kaido the same. What happens in team fight can't be said what will happen in solo fight except maybe Luffy who can be given chance more given he prove himself on fighting by himself.
That's not an excuse, the weapon is useless by itself, it's all on the wielder.Yeah, he did, but said it's the sword, not really him. Zoro even comments about Enma on it's abilities, so hard to use it more his feat if Enma has mind of it's own to cut him down. Actually not really as Scabbards did damage to Kaido the same, but got defeated easily one by one. Team fights can't push you on another tier if your getting help for it.