The buster call will attack the entire island of enies lobby. Who knows what criminals are in Impel Down prison, according to the last cover arc, decent odds a few members of baroque works. This could lead to some crazy fighting times.
Think about it, Crocodile vs. Some strange Marine admiral that uses ice powers... can Crocodile drain the moisture from Aokiji?
Or evn Mr. 2 vs. Sogeking. Ussop ran from him once, would he do it again? Franky vs. Das Bones.