Hopefully this makes stuff easier in the future lolll
More info below (tw for injury ofc..)
Some silly info about him in the Pokémon Universe:
He's a failed Paldean Professor. He kept performing some ethically ambiguous experiments on himself... something about the effects of Pokémon moves on the human body. This is where most of his old injuries come from. The burns on his face and arm are from his ace Chandelure, Pumpkin. Her overheat move unintentionally came out stronger than she had intended, severely burning her trainer. Nathan, of course, forgave her for that, as he had instructed her to do so.
Nathan had been stripped of his title of professor as he was seen as "too unstable" for the job, intentionally putting himself in harm's way. Consequently, he lost the job, most of his money, and kinda went a bit nuts. He travelled around Paldea until he got bored, taking a plane to Galar. There, he did more experiments with a couple of new members on his team: Stinks the Yamask, Trashcan the Meowth, and Doodle the Indeedee.
Doodle eventually brought Nathan to his senses and is still keeping Nathan from doing stupid shit. ("Thank you, Doodle," we all say in unison)
He found Trashcan in a trashcan and honestly resonated with the guy. Nathan really saw himself in the eccentric feline. They both instantly bonded and use each other for emotional support.
Nathan came across Stinks while wandering the wild zones at night. He's a big fan of ghost types and just found the fella interesting. He just can't exactly figure out how to evolve her, though... He finds that Stinks is a good conversation buddy.
Squid had been by Nathan's side for the second longest, just a bit behind Pumpkin. The poor Goodra was definitely stressed about Nathan's experiments and tried to help patch him up to the best of his abilities... When Pumpkin had accidentally hurt Nathan badly, Squid felt guilty that he wasn't out to help control the fire.
Pumpkin was Nathan's starter, finding her as a Litwick. At first, he didn't really realize that Pumpkin was well... shiny. He is... stupid, of course. Pumpkin was Nathan's only Pokémon for a few years before he caught Squid as a Goomy. Pumpkin at the time was a Lampent. When Nathan really started experimenting, Pumpkin always hesitated, as she knew that it might hurt her best friend. After the Overheat incident, she r e f u s e d to use anything else on Nathan, no matter how much he asked. She was thankful for his forgiveness, yet didn't really forgive herself at that.