Eden caught him as an Rattata while traveling through the Johto region. He was first seen battling Erika's Skitty. During the spinoff series, Raticate as an Rattata grew a obession for baseball and wanted to train with Casey while Eden refused. When Team Rocket attempted to steal him and Casey's Chikorita, he managed to save himself and Chikorita despite his trainers' attempt to save them. Eden saw how mature his Rattata was and decided to leave him to train with Casey. Rattata didn't reappear until the final episode where he had completed his training with Casey and had long since evolved into a Raticate while Eden was absent. When Raticate attempted to greet Eden, Eden didn't recognize him and rejected him. Later, Eden realized that his Rattata had evolved and was jealous when Raticate hung out with Casey more. Casey told Eden that he had to make up with Raticate since he had rejected him and she told him how Raticate felt. Eden decided to apologize to Raticate and Raticate decided to rejoin his trainer on his Pokémon journey.
Raticate has an Rattata had a shy personality and often hid behind his trainer. When he met Casey when he spotted her training her Chikorita how to play baseball, he was desperate to play too. Ratatta also proved that he was capable of taking care of himself by saving himself and Chikorita from Team Rocket. When he had evolved, he lost his timid personality and was a more friendly and easy-going Pokémon. His feelings are often hurt easily shown when Eden rejected him and when this happened, he often avoided his trainer. But Raticate still is forgiving and cares for his trainer greatly.