Anime: Her first appearance was in Air Time. She was at the Goldenrod Radio Tower. Ash appeared on her show to talk about his Pokemon and his aspirations.
She also appeared in Will the Real Oak Please Stand Up?. She and Professor Oak were going to do a live show in Maroon Town. Team Rocket got wind of this and disguised themselves as the professor and Mary. With the help of Nurse Joy, a quiz show determined who was the real Oak and Mary.
Mary also appeared in Oaknapped! Professor Oak disappeared before taping a segment for her show, so she asked Officer Jenny, Ritchie and Tracey to help her find him. They eventually learned that he had been kidnapped by Butch and Cassidy.
Manga: In the Pokemon Adventures manga, Mary is the Radio DJ and a famous singer. She is a celebrity and a close friend of Whitney, from whom she received a Smeargle. Gold is a huge fan of hers.