His starter Pokémon was Cyndaquil, received from Professor Elm of New Bark Town at the same time as Vincent and Marina. Despite being close friends, the trio did not travel together and went their separate ways. However, they crossed paths occasionally in his journey, in one of these meetings with Marina, he captured a Weedle who becomes one of his most important Pokémon and eventually evolved into a powerful Beedrill.
In the midst of his journey, Jimmy and Cyndaquil are defeated by a mysterious young man named Silver and his Nidoking who becomes one of his most powerful rivals.
Jimmy then leaves on a a mission to become increasingly strong and eventually gets his Cyndaquil to evolve into a Quilava and then reaches its maximum level to evolve into a powerful Typhlosion, allowing him to fight on equal terms with his rival and win.
Thanks to his efforts, Jimmy and Marina then participated in the Silver Conference a full year before Vincent did.
Again on his journey, Jimmy once again met Marina. Both have a battle where she shows the results of their training, Jimmy still takes the lead defeating Marina's Jigglypuff and almost defeating Wani-Wani yet the battle is interrupted by the actions of a group of Team Rocket who were working nearby. In his attempt to save the legendary Pokémon Raikou, Jimmy is beaten by agents of the organization, but the villains give up temporarily with the help of his Beedrill and take the wounded Raikou to be treated in the Pokémon Center.
During the treatment of Raikou, Jimmy meets the mysterious Legendary Pokémon expert called Eusine, he claims that Raikou attacked by retaliation, but Jimmy denies it and says trust the instincts of Raikou.
When Raikou awakens stunned, Jimmy tries to talk to him but he attacks and tries to escape to the forest. Jimmy, Marina and the others try to follow but are a very angry Raikou trying to prevent Attila and Hun in their plans, amid the battle Jimmy and Marina are saved by Vincent who suddenly arrives.
Through the efforts of Jimmy, Marina, Eusine and Vincent, the Trainers are able to defeat Team Rocket and Jimmy finally gets the trust of Raikou which he now considers his friend.