I think it would be cool if we got a new Pokémon Mystery Dungeon game, adding Pokémon from generations 7-9/10. Curious to see how regional forms and evolutions (especially from Pokémon Legends Arceus and maybe Z-A) could be introduced into the PMD world. Maybe also include gimmicks from the main line series like Z-moves, Dyna/G-Max, Terrastalization, Strong and Agile Style. Maybe even Shadow Pokémon. We already got Mega Evolution in Super mystery dungeon and Rescue team DX, so seeing it again couldn't hurt.