You get it from Cynthia the Pokemon league champion.
Talk to Cynthia near the lake of azelf you have to finish something first to get it or the easy way.
talk to the psyduck
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.
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.
yes you can use action replay on Pokemon platinum
NO
You can use the move sweet scent.
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 obtain the secret potion after defeating the fifth gym leader, whom is located in Hearthome City. To advance, you must use it on the psyducks blocking the path outside of the little Cafe, and they will scatter.
A bit up from the grand lake hotel, you will find Cynthia who gives you the secret potion. Also it will be needed to get to Celestic town, you use it on the Psyduck at route 210. Hope it helped!!
stop being a Pokemon playin douche
Ok, after you get the Secret Potion from Cynthia, proceed on Route 210. That should take you to the Cafe Cabin. Walk to the upper left corner, where the Psyduck are. Press "A" when it asks you if you want to use your secret potion. Note: even after you use the Secret Potion it will still remain in your Key Items section of the bag Hope it helped!!
well you need the secret key for team galactics HQ
You cannot use a potion when battling an opponent because the potion hasn't been programed to work yet in Pokemon crater. You can use it while battling wild pokemon.
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.
You use it in the Galactic Eterna building on the first floor in the upper left-hand corner.
I believe that you go to the kitchen in the Old Chetau.
Use a potion.
you need to get a drill thingy from someone underground and then walk up to the wall and use it but you can only use it once