Where do you get the potion to cure the psy ducks?

To cure the Psyducks in the Pokémon games, you need to obtain a special item called the "Secret Potion." This potion can typically be found in Celadon City at the Celadon Department Store or acquired from certain characters in the game, depending on the version you are playing. Once you have the Secret Potion, you can use it to heal the Psyducks blocking your path.