In my opinion those who will fight Kaido will 100% be;
Luffy, Zoro, Kidd, Killer, Law, Shachi, Penguin, Bepo, Marco, Kinemon, Denjiro, Ashura Doji, X-Drake, Apoo, Hawkins and Yamato; they'll push base Kaido to extreme diff and knock him out but because Kaido is an awakening mythical zoan he'll recover and make short work of them.
After that he'll head to Wano and before he does, he encounters Big Mom and they have a falling out, so they'll Duke it out and she loses and sustains grave injuries but thanks to Big Mom's doctors she gets to live for a couple of weeks although extremely weakened.
Then Kaido heads off to mainland Wano in order to destroy it, and when he gets there Hiyori stands bravely to stop him; meanwhile on Onigashima Luffy wakes up and before he goes after Kaido he meets big mom and she uses a special technique where she gives him part of her soul in exchange of her life force and he becomes something like nightmare Luffy, Momo in dragon form takes him to wano and he saves hiyori in last minute and fights Kaido 1 vs 1 and defeats him