Not sure if it's good to specify the category in the ability, like saying "Type 1" or "Type 2", but I think abilities with conditions like, "If you have more than one opponent, do X" or "If opponent has more than 50 cards in deck, discard their top 4. Otherwise, discard their top 2" could work. Basically I think everything should have to reference particular things within the game itself and not be "meta", since "meta" things are more subject to change in the future.