Just some crazy theory I made that connects the stories of many fandoms I'm in. The tags explain the series/franchises used in this theory, so be prepared for a long one.
If you watch Equestria Girls, you will notice that after Friendship Games, Princess Twilight stops coming over to the human world. In fact, Friendship Games is where the human world's Twilight Sparkle is introduced, dubbed Sci-Twi by both Hasbro and the fans of EQG. And another thing about Sci-Twi is that in her debut movie, she became a monster herself, named Midnight Sparkle as of Legend of Everfree, and while it's no doubt the form of herself that the bronies loved the best about her (trust me, I've seen the blind reactions and they all fell in love with Midnight Sparkle quickly), there was also something intriguing that I noticed about Midnight Sparkle's actions...
(and please keep in mind that I am an Equestria Girls fan, and am only on season two of My Little Pony: Friendship is Magic)
Midnight Sparkle was the one and only villain who had the ability to rip holes into other worlds. Translation: she created portals.
I mean, look at this screenshot from the movie:
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Granted, there's also like 36, 594 other rips between this world and Equestria and possibly rips/portals to other worlds that the movie didn't show and she's using it for her own evil gain and she was already opening gateways with her pendant and the magic in the pendant sorta caused this, but she's still clearly opening gateways to at least one other world, even ripping this giant hole into Equestria.
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I mean, come on, Twilight. You had like ten zillion other rips; why are you making this colossal hole that, in the movie, appears to slowly get bigger with the edges breaking off every once in a while?! Okay, back to what I was saying.
And we know Twilight is in there because Sunset helps bring Twilight back to her senses, back to normal, and back on the good side. So clearly Twilight was still... sorta in control, I guess? I don't know.
But think about it. Like I said, pretty much every other villain had to use other resources to get what they wanted. And Midnight be over here ripping open portals to other worlds to get what she wants, which sounds a lot easier than turning the entire school into a teenage zombie army to go through a portal into a pony world to conquer it (looking at you, Sunset).
