You got to go to the tower in the 6th town and to top and give her the secret potion then she is at the gym
You go to the 6th gym.
Go south, then east from the beach using surf, then go to the pharmacy and get the medicine.
beat pokemon gym leader clay,take on route 6, go through chargestone cave,then you'll be at the 6th gym.
You answer 5 questions in the radio tower in goldenrod city,she'll talk to you and go back into her gym.
After you beat your rival after the 6th gym
go through ice path
You just have to climb the light house, talk to her then go to the pharmacy in cianwood and he will give you the secretpotion.
it's in blackthorn city and you got to go to dragon's den because the gym is closed when you first go there
try specifing which version first. :)
you go to the canclave library
Go through the Ice Cave!Mr. Seidschlag
you go across route 44