You know what, I just realized something:
Mimikyu's dex entries:
Sun: Its actual appearance is unknown. A scholar who saw what was under its rag was overwhelmed by terror and died from the shock.
Moon: A lonely Pokémon, it conceals its terrifying appearance beneath an old rag so it can get closer to people and other Pokémon.
Ultra Sun: Although it's a quiet, lonely Pokémon, if you try to look at what's under its rag, it will become agitated and resist violently.
Ultra Moon: A gust of wind revealed what hides under this Pokémon's rag to a passing Trainer, who went home and died painfully that very night.
Sword: It wears a rag fashioned into a Pikachu costume in an effort to look less scary. Unfortunately, the costume only makes it creepier.
Shield: There was a scientist who peeked under Mimikyu's old rag in the name of research. The scientist died of a mysterious disease.
Basically, Mimikyu kills people by either putting a curse on them or violently killing them if they ever take a peek underneath the rag. So the murder is all said and good, but there is something that is weird.
I know Mimikyu gets weakened from the sun, but they won't outright die. The only time they are weakened by the sun is when a Mimikyu's rag is taken off of its body. So a Mimikyu won't die unless they are extremely weakened.
Also, about killing a gym leader thing. I'm not sure if a gym leader would have 10,000 pokedollars, but if you did kill a gym leader, the authorities would be all over the place looking to whoever did it. If your character did kill a gym leader, I do have a detective character who would most likely be on it and he is the brother of Shade. If Shade ever catches wind of what Sal did, Shade will tell Miel, since she doesn't tolerate Pokemon killing people, even though her moral compass is practical shit.
So did your character actually kill a gym leader or was that bogus just to get your character the help they need? Because if your character did kill someone, I'm sorry but my characters will make sure they will not go unpunished, as justice is very prominent in Shade's family.
Also, if your character has the money, and if store clerks are trained to make transactions for Pokemon in the place of humans, then why can't Mimikyu buy the stuff he needs if he does have the money? Doesn't make any sense.