• English / United States: Serena's Eevee
• Japanese / Japan: セレナのイーブイ
• Japanese (Romanized) / Japan: Serena no Eievui
• Japanese (TL) / Japan: Serena's Eievui

Serena's Eevee is a very Timid Pokémon that is shy to be in front of people and other Pokémon. Serena first saw it dancing on some rocks in a field near Hyakkoku City. She thought it was very cute and that it was light on its feet and it seemed to be having fun. It was very shy, so she lured it by putting out Pofflés that she made and then did her Tripokalon performance to show Eievui her feelings.

Jessie also took a liking to it and also tried to get it by force though. She thought it had exceptional talent that would add grace to her magnificent performances. Serena and her Pokémon protected it for a bit but when Jessie's Gourgeist used Seed Bomb on Serena, Eevee came to the rescue and used Protect to stop her from being harmed.

After being saved by Eievui, Serena asked it again if it would join her on her journey and it agreed. She captured it with her Poké Ball and then let it out to meet all the other Pokémon. It seemed to like Clemont's Bunnelby but Clemont's Chespin got a bit upset when it didn't initially like it.

Evolution into Sylveon

Serena's Sylveon is the evolved form of Serena's Eevee. It's evolution was first hinted at with an ad from the karaoke company Cote d'Azur.

During a Double Battle against James' Inkay and Miette's Slurpuff at the dance party battle round hosted by Monsieur Pierre, Serena's Eevee was knocked down along with Ash's Pikachu. Serena, who was worried for it, came over to give her Eevee some strength and during that time it began to evolve. It wrapped its ribbon-like feelers around the arm of its beloved Trainer Serena and learned the move Fairy Wind in the process. Serena's Sylveon was able to fight back and win the match.