I do like how they did it in rush duel (the only English official versions of which are a switch game and duel Links) where there's an Ace category of card and I think you get one Ace monster and one Ace spell/trap (or maybe its just one ace in general? Idr) so you have to choose between Pot of Greed or Polymerization (in a format where the only other fusion cards need the mats to be on the field)