From Bulbapedia, the community-driven Pokémon encyclopedia.
Yūki (Japanese: ユーキ Yūki) is a member of Team Great Rocket from Pokémon Card GB2: Here Comes Team GR!. She's one of the Trainers at the GR Fire Fort.
Her deck, Fireball Deck (Japanese: ファイヤーボールデッキ), focuses on Pokémon, or specifically the Charmander line, and Pokémon which can use any type of Energy. She refuses to battle the player unless this has only Energy in the active deck.
When defeated, she gives out one We Are Team Rocket booster pack. Also, when defeated for the first time, she opens the door to the next room, allowing the player to reach Shōko.