Probably too old for this. Lots of ideas; no storyline concepts quite yet. The zony mare in my icon has eight legs, because I like the idea of Sleipnirs existing in the 'verse.
Twilight fails to defeat NightMare Moon, and the world is plunged into eternal night. Twilight must travel the world with her friends to unlock the secrets of the Elements of Harmony.
The Elements of Harmony find themselves facing an evil beyond their knowledge, armed with an alien magic. In desperation they use their Elements to summon aid and get - a hillbilly with a silver-strung guitar?