It's pretty difficult to imagine heroic versions of Skeletor and his crew, but the mirror image of Etheria makes a lot of sense.

It is precisely for this reason that it would be a legitimate challenge for any writer to pick up Skeletor and his group of evil guys and turn them into heroes and similarly pick up He-Man and his friends and turn them all into evil villains. It is much simpler to imagine versions evils of the Justice League in the form of the Crime Syndicate of Amerika but no one would ever think of counterparts evils of He-Man and She-Ra and all their companions or versions goods of Skeletor and Hordak and their groups.