Preferably one that’s not a rom hack, though I dig those too. I’m looking for something a bit harder than the originals and maybe a bit more mature, but still fair and whimsical. I’d like a game with pokemon from as many gens as possible, and fakemons are fine too.
If you want something familiar but also completely different, go with Pokemon Emerald Rogue. It does what it sounds like and turns the game into a roguelike.