Vanillish first appeared as a Vanillite in Crisis in the Cold!, where she was seen keeping an eye on Team Plasma, who were hiding out in the Cold Storage after stealing a girl's Pokémon. She soon encountered the group and showed them where Team Plasma was hiding. After Team Plasma were defeated and attempted to get away with the stolen Pokémon, Vanillite froze the ground with Icy Wind, causing them to drop the Poké Ball and flee empty-handed. After the event, Vanillite expressed a desire to go with Bianca, who captured it in a Poké Ball, making it her first caught Pokémon.
In Pokémon - The Musical!, Vanillite, alongside the rest of the group's Pokémon, participated in a Pokémon Musical.
Vanillite participated in its first official battle in Breakneck Breakdance! It battled against a Dancer's Pansage and was initially at a disadvantage due to her fear. With encouragement from Bianca and the rest of the group, Vanillite began fighting back and managed to defeat Pansage, boosting her confidence in battling.
In Lost in the Snowstorm!, Vanillite offered to help find a Spheal who had gotten lost in a snowstorm. Using her ability to see through the thick snow, Vanillite managed to lead Bianca to where the Spheal was. However, a wild Scolipede attempted to attack the Spheal, forcing Vanillite to step in. After being hit by Scolipede's Hyper Beam, Vanillite evolved into Vanillish. Bianca then commanded her to use Icy Wind against the Scolipede, but the attack morphed into Ice Beam instead, freezing Scolipede solid and allowing Vanillish, Bianca and Spheal to escape.
As a Vanillite, she was shown to be a relatively cowardly Pokémon, initially being too afraid to stand up to Team Plasma. However, after some encouragement from Bianca, Vanillite built up the courage to fight back. This shows that Vanillite has a lot of faith in Bianca, despite only just meeting her, as she was quickly inspired by the Trainer. When participating in the Pokémon Musical, Vanillite was shown to have stage fright. Slowly, but surely, Vanillite slowly gained more courage, culminating in her fighting a wild Scolipede, of her own accord, in order to protect a Spheal.
Upon evolving, Vanillish lost much of her timid personality and became much more outgoing and brave. In fact, she even showed hints on aggression during her battle with Scolipede.