>>51072833What I would love is an exclusive city or area after you've filled out your natdex. In my wildest dreams, it would have a pokemon there that you can't capture anywhere else, but I know people would complain about accessibility or just hack the pokemon in.
So, I think what would work best is an area where you can mess around with the game mechanics and experiment with your mons' abilities, stats, natures and whatever without having to do ballbusting grinding, kind of like a developer's room in other games.