From Bulbapedia, the community-driven Pokémon encyclopedia.
Brittany (Japanese: アヤコ Ayako) is one of the three Club Members from the Grass Club, under Club Master Nikki, in Pokémon Trading Card Game.
The player is required to battle with Brittany, in a 4 prize card match, in order to challenge Club Master Nikki. Upon defeat, Brittany awards the player with two Mystery booster packs.
Brittany plays two different decks over the course of the game. Both decks are four prize card matches.
Poison Bee Deck
Poison Bee Deck (Japanese: のこされたみどりのデッキ) is the first deck played by Brittany. Upon defeat, she awards the player with two Beginning Pokémon booster packs.
This is a required matchup to progress the storyline towards fighting GR-2. Brittany can first be found at the dueling table in the communications room of the Grass Club. Defeating Brittany for the first time gets the player information about her superior, Nikki, who is hiding out at Mr. Ishihara's House and will only appear there at this point in the story. This battle therefore must be played at least once to progress the game.
If you challenge Brittany at a later point in the game, she will have upgraded her deck and will no longer use this decklist.
Poison Curse Deck
Poison Curse Deck (Japanese: どくばちデッキ) is the second deck played by Brittany. Defeating Brittany while she uses this deck gets the player a Beginning Pokémon booster pack and a Psychic Battle booster pack.
Brittany begins using this deck at some point late in the story, at which point she will always play with this decklist.