What if Rainbow Dash was born a griffon, and Twilight an alicorn princess? A seemingly small change to two, but with significant ramifications.
Twilight lost her crown over her response to an incident involving griffons' predatory nature, but now she'll have to trust one of them, on top of braving an Everfree full of creatures even more happy to eat ponies, to defeat Nightmare Moon...and it won't be quite the picnic it was in the show.
Expect content akin to No Second Prances (depressed Trixie Manticore mouth dive episode), i.e. somewhat heavy drama/topics and ponies being gobbled up.
This is an entry for Choices: A Species Change Contest.