True. Strangely they didn't go down that route. Though I guess we could also think that's something that "helps" separating them from Digimon for example.
I think it would be weird lol. Pokemon are supposed to be living creatures with personalities in the verse, fusion kinda goes against that. Would be cool tho to have fused attacks in team battles.
Fusion can be very fun though. When I played SMTV it was addicting as hell. (It really makes me hope the next Persona game will launch on Switch…).
I guess the best way to go about it would perhaps be to make a new region based around it. With new Pokémon that form two halves of a whole. That way it’s more of a naturally occurring thing than some mad science experiment lol.