Where Is The 6 Gym Leader In Soul Silver?

But first you must go up the stairs(not elevator)beat the trainers,and when you come to a dead end go to the window to the far right and go out of there.Then proceed through the door(don't forget to get the Rare candy on the other side of the tower there).Then battle the other trainers until you reach the last level, which Jasmine,the 6th gym leader,will be with sick "Amphy".She will send you to get medicine.Fly over to Cianwood and get the medicine at the pharmacy(the potion is called the Secret potion,but do not worry he will give you it if you talk to him).Then go back to the lighthouse take the elevator up,then give the potion to her and watch what "Amphy" does.After this Jasmine will return to the gym.Don't let the traiers scare you as you walk up to her(they just give inspiring words).
      P.S.-Jasmine's team is  two magnemites and a Steelix,so make sure you have a fire type pokemon!!

Olivine city

First you have to get the potion from a man in the sea on Route 41. When you obtained the potion go to the lighthouse and give it to the Gym Leader. After you give it to her she will return to the Gym. Then you may battle her. Be careful, she uses steel types and has amazing defensive pokemon! Good Luck!!

Shes in the lighthouse to the southeast

In olivine city

In olivine city !