Here are the relevant images from this episode of FW Team-Up!
Highlights from DC Comics Presents #47 by Paul Kupperberg, Curt Swan and Mike DeCarlo:
Prince Adam's training regimen. Recognize any toys?
Superman finds himself in Eternia:
The battle begins and alliances are formed!
Oh no! Our heroes at each other's throats!
Superman turns the tables on Skeletor!
The friendly(ish) farewell:
Theme: "Batman: The Brave and the Bold" by Andy Sturmer.
Bonus clips from: "He-Man and the Masters of the Universe" by Filmation, starring John Erwin; "The Battle Begins", "The Final Battle", and "Masters of the Universe Main Theme" (which doesn't sound AT ALL like John Williams' Superman score, right?) by Bill Conti.