At the end of the episode, Lillie arrived at the beach, where Ash and Gladion had held a battle, and became annoyed by the fact that her brother took off so early without saying goodbye. Lillie was troubled by how much more cold and distant Gladion appeared to be from the last time Lillie saw him six months ago, but Ash reassured her that Gladion was still a good person, reminding her of her brother's words of encouragement. Gladion was surprised by the fact that Lillie was able to touch Pokémon again and told her to treasure her Vulpix. Lillie was reunited with her brother in A Glaring Rivalry!. From that point on, Lillie was okay with holding Snowy, though she still froze at contact with other Pokémon. After that, Team Rocket was frozen by Snowy's Powder Snow and taken away by Bewear. When Snowy was blasted off a rooftop by Mareanie's Sludge Bomb, Lillie leapt off after it and caught it in her arms. Eventually they were confronted by Team Rocket, and Snowy used Powder Snow to protect Lillie from Mareanie. Though her fear of touching Pokémon initially persisted, she spent time bonding with Snowy. Lillie officially caught the Vulpix, which she nicknamed Snowy, in Getting to Know You!, making her a Pokémon Trainer like the others. At the end of the episode, her Egg hatched and was discovered to be an Alolan Vulpix. In Racing to a Big Event!, Lillie watched her friends participate in the Pokémon Pancake Race. After several failed exercises at petting Ash's Pikachu, Rowlet, and Rotom, Lillie was able to touch the Egg when she instinctively shielded it from a wild Salandit. In Lillie's Egg-xhilarating Challenge!, Lillie agreed to watch over a newly discovered Pokémon Egg from Mount Lanakila for a class assignment, seeing it as an opportunity to finally overcome her fear of touching Pokémon. She and the other classmates saw Tapu Koko for themselves when it appeared to challenge Ash and Pikachu to a Pokémon battle, during which Lillie advised Ash about Tapu Koko's techniques. In The Guardian's Challenge, after Ash enrolled in the school and showed his new classmates the Z-Ring he received from Tapu Koko, Lillie explained the guardian's fickle and mischievous nature to him. Later, when Ash described an unfamiliar Pokémon that he but no one else had witnessed, Lillie deduced that he saw Tapu Koko, the island's guardian deity. She quickly demonstrated her fear of Pokémon when she cowered behind Ash upon being approached by one of the Tauros, only to be startled by his Pikachu.
Lillie debuted in Alola to New Adventure!, where she tried in vain to warn Ash away from being trampled by her classmates' Tauros as he stumbled upon the school. Despite her fear, Lillie continued to enjoy studying Pokémon and subsequently enrolled at the Pokémon School on Melemele Island. Lillie returned to her Hau'oli estate while her mother remained behind and her brother ran away, leaving her under the care of her family's servants, including Hobbes.