A key item that is used to cure a group of the Pokémon Psyducks' headaches on Route 210 in the Sinnoh region (Pokémon Diamond, Pearl and Platinum).
The SecretPotion is also used to cure the Olivine City's Glitter Lighthouse's sick Ampharos, Amphy. Jasmine informs the player that the sick Pokemon can no longer light the lighthouse and she will not leave until the Pokemon is well again. The player then surfs to Cianwood City and obtains the SecretPotion and returns it to Jasmine. She uses the SecretPotion on Amphy then returns to the Olivine City Gym.