From Bulbapedia, the community-driven Pokémon encyclopedia.
Julie is the opponent in Pokémon Play It! and Pokémon Play It! v2. She guides the player through the basics of Pokémon Trading Card Game.
Julie's deck depends on the one the player chooses.
Pokémon Play It!
Pokémon Play It! v2
Unlike in the original, Julie randomly uses one of the decks available to the player, but not the deck the player is using or the Royalty Deck. The decks available to Julie are the Electric Zap, Flame On, Hit'Em Hard, Poisonpowder, Psychic Dream, and Wet and Wild decks.
However, she does have preset decks in the challenge levels, based on the level selected.