He is a Pokémon Trainer from Kanto training

to become a Pokémon Referee.

Jimmy was a poor Trainer, and often felt he had bad luck. Quite by accident, he came upon an island where Trainers were learning about refereeing. As a referee, he is shown to be quite indecisive. After defeating Team Rocket who had attempted to steal his Pokémon, he decides to revert to his original goal of becoming a Trainer, and return to Lilycove City.