Well, since it would be a group effort, I don't really mind it...
the likes of Kidd don't deserve to be in that spot either by that standard... in fact, only red scabbard + Luffy showed feats to make thm deserving of clashing with Kaido here...
but here we are, scabbards are defeated, and it's Luffy + a bunch of people aiding him... Zoro being there is okay cause I see him more deserving the kidd or Killer or some other supernova joining that fight...
As for Sanji, I honestly don't care if he confronts Kaido... I prefer him having a solo fight against a calamity like King or Queen SOO MUCH BETTER... because it would properly scale Sanji strength for post-timeskip and give him that RANK/STATUS
which he can then surpass later on, but at least we would be able to finally confirm and say "Sanji is on XXX level" for sure...
While the people who will fight against Kaido... since it's a group fight... it will be much harder to scale them and say what level they are on...
I may say that will exclude Luffy because I know for sure what Luffy's level will be:
- Luffy will end up after wano being (generally weaker than Yonko but can tossle with them, HOWEVER, he will have a mode that is ABOVE yonko but is very time limited)... it's always been the case with tough opponents
But as for the rest who will participate in that fight, their damage will be scaled by our headcanon, on how much they affected Kaido.. some people will push their agenda for their character, but generally it will be hard to scale
So, I surely don't mind Zoro's main battle is with group against Kaido... and I prefer Sanji to stay away and face a calamity since Sanji is someone we wanted to scale post-timeskip for a long time