u go to the top of the gym and turn off the waterfall and challenge him.
The Mahogany City gym leader is not in Cianwood. He is in the gym in Mahogany, not anywhere else.
in cianwood city
cianwood city
You battle the 8th gym leader, Clair, at Blackthorn City.
It is on Cianwood City Island. You have to surf there from Olivine City. (NOTE: the gym in Olivine is actually the 6th Gym battle so go to Cianwood Gym first) Before you go to Cianwood City make sure you visit the Olivine lighthouse top floor to talk to the Olivine Gym Leader about a sick Pokemon first.
You surf back to Olivine city and climb up the lighthouse to Jasmine. GIve her the medecine you get in cianwood pharmacy, then go to the gym and battle her. She is steel type so good luck.
you have to use surf keep going untill you reach cianwood city
You get the Fly HM after defeating the Cianwood City Gym Leader. This makes it easier to get to and from the city (since it is past the water)
I think you'll need to give Amphy the medicine in the Lighthouse and battle Jasmine, then you can battle Chuck, which the is 5th Gym Leader in Cianwood City.
At Cianwood city
In Pokémon SoulSilver, after reaching Olivine City, you have to head to the Lighthouse and make your way to the top. Jasmine will tell you how an Ampharos is ill and she asks you to go get some special medicine for it. Head to Cianwood City, get the SecretPotion from the Pharmacy there and you can battle the Gym Leader in Cianwood City first or you can return to Olivine City to give the SecretPotion to Jasmine and Ampharos and battle Jasmine and then return to Cianwood City to battle Chuck there. Go to olivine city. Head to the lighthouse. Top floor. Talk to Jasmine. Go to Cian wood . Get the secret potion. Battle the 5th gym there
surf to cianwood city, defeat the gym leader and then talk to the lady standing outside of the gym
yo need to get the secret potion from cianwood city and give it to ampharos
The Mahogany City gym leader is not in Cianwood. He is in the gym in Mahogany, not anywhere else.
you are going to need the HM surf, and then surf to cianwood city. there will be a pharmacy that gives you the secretpotion for free, but i recommend beating the cianwood city gym leader before heading back to olivine city.
Help Jasmine in the lighthouse by getting the seceret potion from Cianwood City Pharmacy.
To get the Olivine City Gym leader to battle you, you have to go to the top of the lighthouse and help her heal a Pokemon by getting medicine from a man across the sea in Cianwood. The leader there, Chuck, is actually the fifth, and Jasmine is the sixth.