Lily (known also as Lily the Spellcaster) is a character appearing in Pokémon: Master Quest.
Season 5: Master Quest
Lily collected ingredients to make a potion that could help people communicate with Pokémon, however, what exactly her spell was meant to do is unknown. When Ash tries out her spell, he turns, temporarily, into a Pikachu, leaving everyone (including Lily) shocked. However, she assured everyone that Ash's transformation would only be temporary.