Homika

Roxie appeared in Rocking the Virbank Gym! (Part 1) and Rocking the Virbank Gym! (Part 2). She is a powerful Gym Leader, defeating everyone who dared to challenge her with only three Pokémon. When Ash arrived at her Gym, she was thrilled to see his Pikachu, as she too had a Pokémon originating from Kanto, Koffing, and happily accepted his challenge.

Roxie proved herself to be a very capable Gym Leader, defeating five of Ash's six Pokémon despite being at a disadvantage in terms of her party. She would occasionally perform a riff on her bass during the battle, and the crowd would chant her name. When she was defeated she happily congratulated Ash as the crowd cheered for his victory, and she presented him with his eight and final Unova Badge, the Toxic Badge.

(Source: Bulbapedia)