Espeon first appeared as a lost Eevee that ran into Ash and his friends. The Eevee's owner, Sakura, approached the group and Misty returned Eevee to her. Sakura invited the group to a tea-ceremony that Sakura's sisters, the Kimono Sisters, were hosting. Team Rocket was also at the event and attempted to steal the Sisters' Pokémon. Sakura sent out her Eevee to battle them, and it was revealed that Eevee was the only unevolved Pokémon owned by one of the Kimono Sisters, in a similar situation to a previous episode. During its battle with Arbok, Eevee became injured after Arbok defeated it, leaving the protagonists to finish the trio off instead. Later, while Misty and Sakura were discussing about their sisters, Eevee was seen happily playing with Togepi. When Team Rocket came back to steal the Pokémon once again, Sakura sent out Eevee to take on Victreebel. Unfortunately, it was beaten once again. Victreebel then threw Eevee into Team Rocket's Pokémon cages. Eevee was freed by Tamao's Umbreon and Team Rocket's plan of stealing the Eeveelutions backfired. When Ash and his friends left for Olivine City, Eevee and Sakura waved goodbye to them.
Espeon and Sakura
Sometime before Espeon, Not Included, Eevee evolved into Espeon. As Ash and his friends reached Ecruteak City for the second time, they made plans to meet up with Sakura and her Espeon. At Sakura's house, Espeon had a battle with Misty's Corsola. Even though Espeon was about to win, Corsola countered with a combination of Recover and Spike Cannon which took out the Psychic-type. After Team Rocket captured Sakura's sisters' Pokémon, Sakura decided to use Espeon as bait in order to lure Team Rocket to them. During the battle with Team Rocket, Espeon teamed up with Corsola and took out Arbok and Victreebel, leaving Pikachu to finish the trio off. With Team Rocket defeated and sent blasting off yet again, Espeon freed the captured Pokémon using Swift. Seeing Sakura's bond with Espeon, the sisters decide to let Sakura set off on a journey of her own.
In The Blue Badge of Courage, Espeon accompanied Sakura when she wanted to have a rematch with Misty for the Cascade Badge, as they were confident they could win the Gym battle. Unfortunately, Misty did not have any Cascade Badges left. Sakura, Misty, and Tracey went to Rifure Village to retrieve more badges. Once there, Espeon found the badge maker, Kinso, and saw that he had injured himself. Kinso told the group that they would have to make the badges themselves, and Espeon helped the group do so. Later, when the Gym Badge thieves stole some of the newly-made Cascade Badges, Espeon teamed up with Misty's Psyduck to take on their Zigzagoon and Poochyena. Espeon and Psyduck were victorious and the group left Rifure Village with their hard-earned Cascade Badges. Back at the Gym, Espeon battled Misty's Corsola and won, earning Sakura the Cascade Badge. Espeon was last seen leaving Cerulean City with Sakura and Tracey, after saying goodbye to Misty.
Personality and characteristics
As an Eevee, Espeon was very energetic and outgoing. It often ran off, as seen during its debut episode. After evolving, it became more skilled and agile in battle, allowing it to face stronger opponents.