From Bulbapedia, the community-driven Pokémon encyclopedia.

Gary's cheerleaders (Japanese: シゲル応援ギャル Shigeru's cheering gals) are a group of girls that follow around Gary Oak on his Pokémon journey. Their main purpose is to cheer Gary on, much like real-life cheerleaders at sporting events. In the original Japanese, they are played by 大谷育江 Ikue Ohtani, 飯塚雅弓 Mayumi Iizuka, and others. They are all played by Veronica Taylor in the 4Kids English dub.

They made their debut in the first episode. They were seen outside Professor Oak's Laboratory cheering for Gary as he received his starter. Their motto is "Gary, Gary, he's our man. If he can't do it, no one can".

His cheerleaders support Gary very much, and they are deeply hurt when he loses one of his battles. When he lost his gym battle to Giovanni, the girls burst into tears. They also did this when he lost the Pokémon League.

The cheerleaders then disappeared for most of the Johto League. They finally reappeared in The Ties that Bind to cheer Gary on during his battle against Ash during the Silver Conference. Unlike the previous battles, they did not start crying when Gary lost to Ash. Gary appeared to finally get rid of them when he decided to become a Pokémon researcher like his grandfather.

They have also had appearances in Dig Those Diglett, Attack of the Prehistoric Pokémon, and Riddle Me This.