In Off the Unbeaten Path, May and Eevee competed in the Pokémon Orienteering Contest, with the goal being to find five checkpoints spread across the island. After obtaining all but one of the checkpoints, the two meet up with Max and Munchlax, who still need two more. While discussing it, Jessie and Team Rocket show up and cut the bridge they're standing on. Ash and Brock show up just in time to save them, after which they are approached by Swellow, who informed them Team Rocket was up to no good. Due to this, the group ended up abandoning the race.
Eevee made its stage debut in What I Did for Love!, in which it went up against Brock and his Marshtomp in the Gardenia TownPokémon Contest. Although Marshtomp could use its fins to sense Eevee's underground movements and detect exactly where it would come up after using Dig, Eevee eventually scored a win for May.
In Strategy With a Smile!, May used Glaceon in the finals of the Wallace Cup, where it went up against Dawn's Piplup, in its first battle as a Glaceon. The fierce battle concluded with Dawn as the winner, though Glaceon lost the match by only a few points. Although Glaceon was saddened by the loss, May said that it did great.
As an Eevee, Glaceon had the typical traits of its species: playful demeanor, affection for its Trainer, and loyalty. It was also quite energetic. Being a recently hatched Pokémon at the time, Eevee had great curiosity as shown by its fascination for the ocean.
Upon evolution, its personality changed moderately. While Glaceon retained its loyalty and affection for its Trainer, its playful demeanor had been replaced by a more assertive and slightly aggressive one that shows mostly during battle.
Description: Eevee would use Shadow Ball and Munchlax would use Focus Punch. The energy from the Focus Punch would fuse with the Shadow Ball and hit the opponent with the power of the Shadow Ball and the Focus Punch.
Of all the main characters' Pokémon that debuted as Eggs, Glaceon took the longest to hatch, at seven episodes.
Glaceon is the first Pokémon belonging to a main character that has evolved by being in a certain location (in this case, near an Ice Rock).