Cynthia is the Champion so you will see her when you beat the Elite Four
from Cynthia
you get secret potion from Cynthia after you chase galactic grunt in pastoria city
Yes you do. You have to talk to the Team Galactic guy near the Great Marsh and chase him and he'll lead you to Cynthia. She gives you the Secret Potion.
At Valor lakefront, Cynthia gives you the secret potion. Give this to the psyducks by cafe cabin, and go down that road until you get to celestic town.
well you have to get the secret potion from Cynthia in solaceon and use it on the psyduck that are standing in the way after you've done that Cynthia will come and give you the old charm and she'll say I want you to deliver that to my grandmother in celestic town.
After you beat the gym leader in Veilstone {or Hearthome i cant remember} Cynthia should give you a secret potion. Then you go to the Psyduck and you push A. Then you can carry on from there. I hope I helped!!!
There is no legitimate secret potion cheat for Pokémon Diamond, Pearl and Platinum version. One way to do this would be to use an Action Replay.
You have to get the secretpotion from Cynthia. To get it you must continue on with the story. Use the walkthroughs. When Cynthia gives you it you have to go up to the psyducks and press A it will ask you if you want to use the secret potion on them, It has no other use anyway so i would use it, u also gotta use it to get to celestic town and continue with the story.
The Psyduck are at the northern part of Route 210, standing in the way of the path. These are the Psyduck you will need to use the Secret Potion on.
she is in the pokemon league
you give them the potion that cynthia gives you.
you need to get a secret potion to cure the kcklon just like in damond and pearl ecxpect psyduck