From Bulbapedia, the community-driven Pokémon encyclopedia.
Nishijima is a member of Team Great Rocket from Template:Card GB 2. He's one of the Trainers at the Colorless Altar.
His deck, Snorlax Guard Deck (Japanese: カビゴンとおせんぼデッキ), 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 Pidgey, Spearow, or Double Colorless Energy cards).
When defeated, he gives out two Legendary Power booster packs.