I'm not sure if you have any plans for this but please try to incorporate Shadow Mewtwo from Pokken in any way.
Maybe have the MC go to the Ferrum Region on his way to Alola or smth and he runs into Nia, probably bones her as well. But Mewtwo goes out and finds Anne being corrupted by the Shadow Sy ergy Stone and saves her but gets corrupted herself. So the MC has to go on a whole quest to reforge the Pure Synergy Stone and save Mewtwo. Maybe boning some playable characters from Pokken along the way like Decidueye, Braixen, Pikachu Libre, Ect.
I know this is INSANELY UNLIKELY TO HAPPEN but I'll take any kind of Pokken Appreciation, no matter how small.