Blue, who encountered Koga, sent Scyther to attack him. However, the figure was Grimer, who grappled Scyther and Blue, preventing them from attacking, moving or sending Pokémon out. Grimer held Blue, as Koga had Golbat attack Blue. Since Red interrupted, Grimer held him as well. However, this made Blue able to send Pokémon out, and Koga was soon defeated.
None of Grimer's moves are known.