Why hasn't there been much co-op integration to the games? Even as a secondary mode in a battle tower equivalent, it seems to be an ignored possibility.
Do you think an entire game with co-op capabilities would work? It could definitely increase the amount of gimmick battles outside of just doubles, too. It'd certainly require a balance overhaul, like potentially capping players to only carry 3 Pokemon each during co-op, and having every NPC carry more.