You can find the Eighth Gym Leader, Clair, at Blackthorn City. But first you will need to battle and defeat Team Rocket in Goldenrod City, save the director of the Radio Station, and he will give you the Silver Wing. Now go to Mahogony Town and go through Ice Path. You are now at Blackthorn City. Clair will be in the Gym to battle after you've completed that mission.
Sunyshore City, but you first have to get him from the Light House after talking to Flint in front of the Gym.
Sunnyshore city. You can find him in the lighthouse, north-east end of town. Talk to him, and he'll go back to his gym, where you may fight him.
Viridian city. Its Giovanni of team rocket, and he has a Dugtrio, 2 Rhyhorns, a Nidoking and a Nidoqueen, all levels 42-54
he is at the top of the lighthouse in sunnyshore city
the 8th gym leader in Pokemon platinum is in sunyshore city
the seventh gym leader in the johto region is in mahogany town
the seventh gym leader in the kanto region is on seafoam island
The Eighth gym leader is in her gym. She is not in any special location. However, she will go into the Dragon's Den at one point, but only after you defeat her.
in blackthorn city in johto
up your Pokemon game
The fifth gym leader in Pokemon platinum is crasher wake but you get the fourth badge.
First you have to battle the snowpoint gym leader
beat the first gym leader in oureburg city he then gives it to you
Maylene is located at Veilstone in Pokemon Platinum. Maylene is a gym leader and is unaware of the amount of strength she possesses.
Pastoria city
volkner
Defeat the 8th
The fifth gym leader in Pokemon platinum is crasher wake but you get the fourth badge.
the 8th gym leader is the last
beat the 8th gym and then go up and there is a person from hoen and also gym leader will give it to you
The water Pokemon gym leader is in Pastoria City.
Wallace is the 8th gym leader PEOPLE!!!!!!!!!!!
The Gym Leader of the Snowpoint Gym.
The eighth gym leader in Pokemon platinum is the one in sunny shore city.
After You Defeat All The Gyms Jasmine The 8th Gym Leader Of Johto Should Give It To You.
the 8th gym is closed because you have to beat all other 7 gyms and then it will be open p.s. the 8th gym leader is giovonni
You use your strong(est) Pokemon to kill the Gym Leader's Pokemon.