"Hercules and the Living Legend" is an episode of Hercules: The Animated Series
Hades realizes from a convention Hercules and Phil are attending that Phil is the key to Hercules' success in training to be a hero, as he teaches him. So Hades visits an old student of his, Achilles (Dom Irrera), who is now a washed-out has-been. Hades offers him his old body and capabilities back, and when Phil is visited by Achilles, he begins to spend more time with him, pushing Hercules to the side until he finally decides he no longer needs a trainer. However, Hades is foiled by them getting back together after Phil realizes he can't leave Hercules on his own, and he returns Achilles to his old body. Memnon, a monster from earlier, takes on Hercules and Phil on the training field, and when Hercules is knocked out, Achilles, realizing what it means to be a true hero, steps in and defeats the monster. Achilles then decides to deal with a flood situation in Acadia (ironically caused by Hercules).