I'd laugh if Zoro, Sanji, Kawa and Izo all fought just King, but I think all 4 will be crucial to fighting both King and Queen. I'm just gonna leave it at that. It does seem to me that these 4 will be paired together until those 2 are defeated. Seems like Sanji needs to help Zoro first but we need dialogue.
In the end it'll probably be just the 2 strawhats vs King and Queen anyway