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Pokemon Musous as a new spin-off title.
6 released at once for all six generations so that the game doesn't have issues with all the characters. Gen 6 has access to all mega evolutions to swell its numbers, whereas other gens only have mega evos of mons of their generation. Simple gameplay, pick a mon, rampage across battlefield. Plotline could have Giratina, maybe Mewtwo/Deoxys, or fuck even Arceus if you wanna go full fedora.