Luffy Zoro and Kid are the ones who openly declared they wanted to fight / take down Kaido
Although it was his initial plan, Law never truly aimed for it, since his real aim was Doffy, and he ended up entrusting Luffy for it, so I could see Law accepting to hold off / fight Big Mom especially since he is the one who brought up this idea
Killer can fight whoever he wants, but I assume he'd want to follow his captain and thus due to balance purposes I'd assume Kid could end up fighting Big Mom. He'd obviously be reluctant at first due to his initial goal but I can see Oda finding an excuse for him to be forced to fight BM especially since they share a backstory(Kid taking something from her, wounding a SC, sinking her ships)
So I'd say this split up could make the most sense
- Luffy and Zoro vs Kaido
- Kid and Killer vs BM
Law could be the wildcard between both fights
With that said I'm not convinced by this translation because it's not like splitting up helps that much since whatever the split, the groups would be reduced in numbers and thus if they think they can't win even in a 5 vs 2, I don't see how it'd help to do 2 or 3 vs 1 setups
That's why I won't be surprised if the translation was messed up and the the "remove one" is the correct one
If one is removed, it makes sense why their chance would increase, if one is removed, it makes sense why Toki / Oden's 9 shadows foreshadowing never involved BM
We just have to wait for the official translation to be sure though