By beating the trainers before their leader of course, like any other gym. Since they only use fighting pokemon a flying and a psychic pokemon should do the trick.
The Mahogany City gym leader is not in Cianwood. He is in the gym in Mahogany, not anywhere else.
The seventh gym leader is situated in Snowpoint city.The 7th gym leader, Pryce, is in Mahogany Town. To get there, you go east of Ecruteak City. You will have to pass through Mt. Mortar. After you get to Mahogany Town, you have to beat Team Rocket in the shop in Mahogany Town and at Lake of Rage north of Mahogany Town.Hope this helped! =)
In the mahogany gym
Pryce of Mahogany City Gym
Ya can find the final gym leader, Clair at blackthorn City. Head west from mahogany town and go through ice path. Hope I helped! :)
in the league
You have to beat the lake rage mission.
you need to beat the mahogany gym than go get your picture taken in goldenrod city
you have to battle the red gyrados then get to team rocket's base and get through it then you can battle in the Mahogany gym the get to pryce
The gym leader of Mahogany Town. He uses Ice-type Pokemon. You face him as the 7th gym leader in the game.
by beating the icicle gym leader. In mahogany town.
Mahogany town