While Silver, the rival in Johto, is male, 4 is called female by players. She is the daughter of Giovonni. Some say she is a girl in disquise, to look like a male, similar to Yellow from the Pokemon Adventures manga.
4's starter was Aipom, but became Houndoom and Kricketune in later rematches.
Role in Heartgold
4 broke into Professor Elm's lab and stole an Aipom. She ran into Ao in Cherrygrove town, but lost against her Trapinch. She hates her father and Bill, and despite her seeming like a villian, she is trying to stop both of them. She helped Aoooo during the battle of Goldenrod against Team Rocket.