Roxanne is the Gym Leader of Rustboro City and oversees the Stone Badge. She's known for her expertise with Rock-type Pokémon—her name itself hints at this specialty, possibly derived from "rocks." Interestingly, her Japanese name references both azalea flowers and the word for throwing stones.
In the Pokémon Adventures manga, Roxanne juggles two roles: running the Rustboro Gym and teaching at the Rustboro Trainer's School. She shows up across several chapters, most notably in the Nosepass battles and later when she teams up with other Hoenn Gym Leaders to fight Team Aqua and Team Magma. One of her defining quirks is that she supplements traditional gym battles with written tests—she's as much about knowledge as raw skill.
The anime portrays her similarly: Gym Leader by day, teacher by night. She runs an introductory Pokémon course for kids who aren't yet old enough to be trainers, drawing on what she learned as Professor Oak's star pupil. Her main anime appearances are in episodes 291-292, where Ash challenges her for the Stone Badge. The first episode mostly focuses on her students, but the second kicks into the actual gym battle—Pikachu's Iron Tail attack ends up being the deciding factor against her Nosepass. She also admires Brock as the strongest Rock-type Gym Leader out there, which says something given her own credentials.
Content compiled by AnimeList.moe from publicly available sources.