Like most Ghost Pokémon,
Officer Jenny's Gastly likes appearing out of no where and tries to be the center of attention even when
Officer Jenny is discussing official police business.
Officer Jenny always has to fight with its playful nature so she can do her job.
Gastly wasn't affected like the other Pokémon by Team Rocket's Hypnotic waves because Ghost Pokémon are strong against psychic type attacks. Gastly found both
Jessie and
James lying in the street unconscious after
Butch and
Cassidy kicked them out of their base. Gastly played an important role in defeating Team Rocket by stopping the combined attack of all the controlled Pokémon from hitting
Ash Ketchum and the others. It then broke down the front gate to allow the captured Pokémon to escape the base.