There won’t be any real matchups, although basically every character on Egghead has potential to at least clash with a Gorosei.
The Ancient Robot is seemingly the last player that can enter the stage, and we’d imagine that it’s the thing that can hold them off long enough for the Strawhats to escape, which it surely has to be bar another factor somehow showing up.
The big question is still Saturn, I think. He’s getting replaced by Devon at some point, we all know that. Is that now something that’s happening further down the line? He’s still the main villain of this arc, regardless of the rest of the Gorosei showing up. Can Oda manufacture a situation where Saturn falls here in a manner that still lets the Blackbeard’s impersonate him further down the line?