Quote Originally Posted by Rater202 View Post
I still want the spin-off game where mad scientist kidnaps a kid and fuses them with a Pokemon or otherwise turns them into some kind of hybrid with endings based on whether you stay fused, separate, or fail to escape from the bad guys.

There are a lot of concepts in Pokemon that are only around for one or two generations and never get fleshed out despite being super cool. We get a human accidentally fusing with a Pokemon in gen one and multiple pokemon being fused together in SwSH, so clearly, this kind of thing is plausible in the lore.
The bot post that brought this to my attention in a notification email was gone by the time I checked the thread - but you might want to check this fic, Mercury: http://archiveofourown.org/works/44996500