She-Ra: Princess of Power (1985)

S1E35 Gateway to Trouble

Skeletor hatches a scheme to banish the Royal Palace to Etheria using a Gate-Maker device. However, his plan unravels when Modulok betrays him and joins the Horde. Tracking the traitor through the portal, Skeletor finds himself stranded on Etheria, forced into a tense, uneasy alliance with She-Ra and He-Man to retrieve the device and stop the Horde from seizing it.