There are some signs which say mugis would fight against kaido:
1) Mugis have defeated relative easy the kaido subordinates and with little relevance (for example franky vs kumadora or baby5 had more relevance than franky vs sasaki)
2) Marco words: there are a lot of people than they think marco will fight against kaido due he said than now he doesn't fight with him but marco also said than mugis (not only zoro) are the main fighters and they must go up on the rooftop
3) Yamato meet the mugis and she says they are strong: Yamato should need to know it isn't only luffy if not the another mugis are also strong
4) Kaido recognise the another mugis (and not just luffy and zoro)
5) Toki prediction: The toki prediction said: Like the Moon, you are ignorant of the Dawn. If there is one ardent wish that must be fufilled, it will be when nine shadows are cast woven together through twenty years of moonlits nights. Only then shall you understand the radiance of Dawn. With luffy there are nine.
@Le Fishe D. Crydo @Cinera @Finalbeta @Zoro D Goat @Peroroncino @HA001 @Hahasanji @RayanOO @Natalija