After beating the 5th gym, head north to Chargestone Cavern. After getting through there, you have to travel north to the Celestial Tower where, at the top, you will find the gym leader. She will return to the gym where you can battle her.
sixth gym laeder
In Pokémon White 2, the 6th Gym can be found in Mistralton City.
the 6th gym is in canalacve city
The 6th gym is in Saffron City the gym leader is Sabrina she uses Psychic type pokemon.
Her name is Skyla and she says that a Pokemon is hurt on top of Celestial Tower. If you go up with her, she will already heal that Pokemon. Then she will tell you to challenge her in her Gym.
The fifth gym in Pokemon white uses the ground type.
You cannot rebattle Gym Leader in Pokemon White.
The 6th gym leader is in Fortree City.
in the gym
Well,it was easy for me I don't know if you have this Pokemon darnanitan level 40 you can kill them in one shot:)
The 6th gym leader is in Canalave City.
The Unova gym leaders are; !st gym: Cilen, Chili, and Cress 2nd gym: Lenova 3rd gym: Burgh 4th gym: Elesa 5th gym: Clay 6th gym: Skyla 7th gym: Brycen 8th gym: Drayden(pokemon black) and Iris(pokemon white)