From Bulbapedia, the community-driven Pokémon encyclopedia.
Samejima (Japanese: サメジマ Samejima) is a member of Team Great Rocket from Pokémon Card GB2: Here Comes Team GR!. He's one of the Trainers at the Colorless Altar.
His deck, Sudden Growth Deck (Japanese: きゅうせいちょうデッキ), focuses on Pokémon. He refuses to duel against the player unless this has four cards of the type he has chosen at that time (he can request either Jigglypuff, Dratini, or Mysterious Fossil cards).
When defeated, he gives out two Psychic Battle booster packs.