How did Pokemorphs come to be?
Unknown, even by the Pokemorphs themselves- it’s a subject of debate amongst them similar to how humans themselves debate their origins. Perhaps they evolved naturally from Pokemon. Perhaps Arceus created them fully-formed. Perhaps some unknown agent forcibly altered them from simple Pokemon. We really don’t know- and dwelling too long on it is really missing the point of PCA- High School Drama and super powered fighting action. If you, in your stories, state the origin of Pokemorphs explicitly, you might create resentment in others for favor other ideas, so think hard about before you do it, and if it’s really important for your work. Realistically, if this is ever revealed, it’d be most appropriate if the groups as a whole (or at least a majority) decide upon it, and it is revealed in an epic storyline- something unlikely to happen.