I'm new in Pokemon Emerald. I have a Torchic, Poochyenya, Wurmple, Marill, Ralts and Nincada. But all of their moves are normal types or poison and bug. I wonder that how can I beat that gym leader quickly? Hope you answer.
Marill learns Water Gun at level 10, and Torchic evolves and learns Double Kick at level 16, both of which are super-effective on Roxanne’s Pokémon.
You're in luck. Beautifly learns Absorb by level up after evolving from Silcoon. Because Beautifly has a quad weakness to Rock, Absorb is a viable move for Beautifly, especially with a 4x type advantage against Geodude because Absorb is Grass. Torchic evolves into Combusken a part Fighting type Pokémon and learns Double Kick by level up, which is super effective against Roxanne's entire team. Then you got Marill. Marill learns Water Gun by level up, which also has a 4x type advantage against Geodude as well. What you can do too is getting Beautifly and Marill to at least level 12 as well. That way whenever you eliminate the Geodudes, you can leave Nosepass to Combusken.