you find them near the top of solaeceon town
You get the potion from Cynthia at Valor Lakefront. Then go to route 210 where the psyducks are.
After you have defeated leader wake in pastoria city, Cynthia will give you a secretpotion, go to the psyducks and they will go away
north of soloceon town
If you mean the Psyducks blocking your way in Pokemon Diamond/Pearl/Platinum, they're on Route 210. ..However, you need to specify the game to get a precise answer.
you can usally run into psyduck in lakes. there is the great marsh though.....
It's for the Psyducks to the side of the moomoo milk cafe.
I don't have Pokemon Diamond,but my guess is up Solaceon Town,just keep on going north.But to get to Celestic Town,you have to beat a Galactic Grunt in Pastoria City.Then Cynthia gives you some kind of SecretPotion to give to the Psyducks.
You can find Psyducks and Golducks in the Safari Zone
Beat a Gym Leader, Cynthia talks to you, tells you to visit her grandma in Celestic town, and gives you a Secret Potion. Use it on the Psyducks and you can get past them.
Cynthia(pokemon league champion) will give it to you when you follow the team galactic grunt from Pastora City.
rt. 210 is above Solaceon Town. it is block by psyducks until you can cure their headaches with the secret potion
Go to that town near mt. cornet at the top, (past the psyducks) you give the thing to that women, she will give you surf