I don't have all the details worked out for my trainersona but a ref sheet is in the works!

Basically they were just living their best life going through Unova until Team Plasma said "haha experimentation go brrr". I actually wrote some chapters of a fic about it but basically I had this lil' idea that Team Plasma began experimenting on ways to actually get rid of potential competition from aspiring trainers after their first defeat- they took DNA splicing to a whole other level, making Colress study the DNA of ditto and Zoroark. Because Ditto is an amoeba it was hard to work with, but they ended up finding out how to replicate the transformative dna found in Zoroark's ability illusion. I'm pretty proud of myself for that bs science.
The basic thought is "Pokemon can't be trainers, get rid of the trainers, make them Pokemon and steal their team. perfect."
Anyways, my trainersona was one of the first successful cases.