Here are some Pokemon you should use:
Pikachu/Raichu/Plusle/Minun (I'd go with Minun beacuse of it being a Special sweeper)
Geodude/Graveler/Golem/Camerupt (Rock types are very durable, just use Rock Throw & Cmaerupt learns Rock Slide as an evolution move at Lv. 36)
Blaziken/Camerupt (Just for her Skarmory)
Any Pokemon with an Ice type move or a Dragon-type (Being it so early in the game, and Snorunt doesn't appear until Shoal Cave in Mossdeep, and Ice Beam doesnt appear yet, just go for brute force and hope it works)
Moves to use:
Thunderbolt
Rock Throw/Rock Slide
Flamethrower
Ice Beam (for her Altaria)
Don't get worried if she uses a Potion, just use the same move, and you'll knock her out, and you've earned Badge No. 6 ! And you can use Fly. Teach it immediatly to any Flying-type (Swellow does best, and you should have once, hence, it was important to beat Brawly)