Mihawk is the strongest swordsman, meaning that he is the best in the world in his field but Kaido is the
strongest creature in the world, meaning that nothing that is put alone against him can win. Neither Big Mom imo, cause she is the woman with the
strongest family, is more of a defensive power.
We have "seen"
them go all out 1v1 for 3 days and was a stall. But if you put them in Punk Hazard for 10 days (just like Sakazuki and Kuzan) there would be a winner and would be Kaido cause he is the
strongest creature and even after a long and lethal fight (cause they are on equal level) he will be at the top, again, if it's a 1v1.
But alliance doesn't have this problem: it will be a team battle. None will have ALL the credits.
Finishing blow goes to only one person (Luffy), obviously, or at most a combined blow (but Luffy is still there).
This, tho, will not mean that he is on his level. No one in Onigashima will be on his level by end of war except Big Mom, but here even Oda doesn't know what to do with her imo
All of them will be stonger after this win and the void of Kaido's power will have BIG consequances. For all of them