User blog comment:Magma MK-II/Characters that shouldn't be here, Part 4: Electric Boogaloo/@comment-366087-20160112004334/@comment-34097347-20160112012637

"Possessed/Brainwashed characters only count as villains if they spend more time under the influence in the story than they do with their normal personalities and thus are better recognizable in their possessed/brainwashed states"

In short, if the corruption is temporary/brief then the character doesn't belong here.

I'll refrain from giving a verdict on anything MLP related, not only because I'm not familiar with the show but also because I have a personal disdain for it.