*Giggle* a goose-stepping Nazi pony? That's Hilarious!!! Love it!!! - - Auto Merge - - I always liked the fact that G1 cartoon was rather dark. Lots of demonic-looking villains.
A good way to follow on the "Equestria Girls" movie would be to introduce a human villain who comes to Equestria on a vendetta to exterminate all Ponies.