go to the left of moo moo milk shop, then give the secret potion to the psyduck :)
Chat with our AI personalities
Cynthia will give it to you.
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!!
you have to give them a secret potion that you get from Cynthia
Go to the lake by the city where crasher wake is and i think after u beat the galactic grunt she gives u the medicine from the shop in johto
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.