Glalie was first seen in Let it Snow, Let it Snow, Let it Snorunt!, on Izabe Island as a Snorunt. It followed Ash and the gang through the snow to the Pokémon Center, where it began to cause trouble and stole Ash’s badge case. Once Ash, Pikachu and Corphish cornered him, Snorunt froze Ash’s Stone Badge, threw it in to the air and escaped with the rest of the badges using Double Team. Snorunt then started dropping the badges one by one to make its “game” more interesting. After a small meeting with Team Rocket, it froze Ash with Icy Wind and left the Center through the window into an oncoming snowstorm. Ash follows him and they end up lost in the snow. After Ash got knocked unconscious by protecting him from a small avalanche, Snorunt took him to a cave, safe from the blizzard. After Ash awakes, Snorunt hands him some apples and while Ash begins to trust the mischievous Pokémon, Snorunt runs off into the blizzard with his hat. He takes the hat back to the Pokémon Center and then leads the gang to where Ash is. Reunited, the gang scold Snorunt and ask for the other badges; however they are interrupted by Team Rocket when they capture Snorunt and Pikachu. Snorunt quickly escaped and saved Pikachu, before battling Team Rocket’s Pokémon. Later on, Snorunt still refused to return the badge case, so Ash battled him and subsequently caught him. He was introduced to the gang's other Pokémon at the end of the episode where he continued to prank everyone.
In the next episode, Do I Hear a Ralts?, Snorunt joined Max in his effort to get an unwell Ralts to a Pokémon Center.
Snorunt’s first Gym battle was in The Great Eight Fate! against Juan. It battled along with Pikachu against Sealeo and Seaking but was unable to do much before it was defeated.
In Date Expectations, Ash began trying to teach him Ice Beam. While learning the new move, Snorunt ended up freezing people multiple times, including his trainer and Anthony. Finally in Rhapsody in Drew, Robert gave him some words of advice on how to focus the attack while battling Team Rocket during the Grand Festival, Snorunt then evolves into Glalie and sends them blasting off with its newly mastered Ice Beam.
Glalie had several battles in the Ever Grande Conference and proved to be quite a powerhouse in Ash’s team. In Shocks and Bonds, it teamed up with Grovyle to battle Clark and his Pokémon, Quilava and Charizard. After Grovyle is knocked out, Glalie ended up battling Charizard one on one and eventually won. Later, he battled Katie’s Misdreavus and although he defeated it, Glalie still fell to the effects of Destiny Bond. In Ash’s battle with Morrison in Choose It or Lose It!, he was sent out to battle Morrison's Metang and after a long battle, won the match for Ash. In Ash’s next battle, with Tyson, Glalie was sent out to battle his Sceptile, where they drew after a massive collision of Ice Beam and SolarBeam.
In The Right Place and the Right Mime, Ash left him at Prof. Oak’s laboratory, before he went to challenge the Battle Frontier.
He returned to Ash’s team in An Old Family Blend! for the Lily of the Valley Conference. Upon seeing his trainer, he froze him with Ice Beam, which Torkoal later thawed him out. In Working on a Right Move!, Glalie was seen training with Torterra and Infernape before Ash’s battle with Conway. Ash was initially going to use his Glalie because of its power, to try and overwhelm Conway, but changed his mind as he knew that he couldn't depend on sheer power alone. In the end, Glalie was not seen participating in the Lily of the Valley Conference.