I think it would be woeful writing, tbh. A colossal damp squib to what has been a storyline eight years (there's actually an argument to be made the entire series has built up to this in some respects) in the making.
I don't overly care whether they solo their opponents. If Jinbei fought Smoothie instead of Jack, I'd be a bit disappointed, but could live without that as a conclusion to his storyline with BM.
But the fights this arc should, 100%, be the Strawhats taking centre stage and defeating the Beast Pirates. And if Luffy can defeat Kaido, be that with help or not, then his crew should be able to accomplish the same feat respective to their individual levels.
Luffy vs Crocodile
Pell vs Mr 1
Chaka vs Mr 2
Zoro vs Mr 4
Luffy vs Lucci
Pauli vs Kaku
Tilestone vs Jabra
Zoro vs Kumadori
Sanji vs Fukuro
That's what a non ZSJ vs Calamities, non other Strawhats vs TR suggests to me. It would be garbage.
I know people will say, ah, but what about Dressrosa? That's the other big fighting arc. Fair enough, but even without half the crew Zoro beat the strongest subordinate there in Pica. Usopp took out the most important subordinate in Sugar. Franky beat the guy guarding the factory (a main objective of the arc), who had a claim to be the "best of the rest." Even Brook beat Jora before leaving the arc early. It's only Robin of the ones who stayed on Dressrosa that was shafted with fights, only getting to play backup to Kyros.