From Bulbapedia, the community-driven Pokémon encyclopedia.
Sam (Japanese: ミカサ Mikasa) is one of Dr. Mason's technicians. Mark must battle him in a tutorial match at the beginning of Pokémon Trading Card Game and Mark/Mint can choose to battle him in a tutorial match at the beginning of Pokémon Card GB2: Here Comes Team GR!. He uses Sam's Practice Deck (TCG).
Sam can be dueled at any time. After being defeated, he will reward the player a Colosseum booster pack containing only Energy cards.
Battle sprite from Pokémon Trading Card Game
Battle sprite from Pokémon Card GB2