Hercules and the Pool Party

Hercules and the Pool Party is an episode of Hercules: The Animated Series that first aired on September 17, 1998.

Summary
Hades invites all the gods except Trivia to a pool party in the Underworld. While there, they swim in the Pool of Forgetfulness, hence forgetting who they are and causing chaos in the world above while Hades uses the party to take over Olympus. Hercules meanwhile uses this as a chance to complete labors needed to enter him and Phil in a hero convention; Trivia, overhearing Hades' plan, warns Hercules about it. They visit the Underworld to find the gods have lost their memories; Trivia deduces that sweating will return it to them, and takes them to Hephaestus' forge. With the gates of Olympus locked by Pain and Panic, Hades has Hephaestus try to open them and confront Hercules when he arrives. The ensuing fight inadvertently opens the gates, but Trivia stops Hades while the gods arrive, having their memory and positions restored.