When an old friend visits Discord the two of them place a bet over who can cause more chaos. This leads to evil and monstrous alternative versions of main six from different universes to be brought to Equestria and live along side the native main six. However their true nature isn't told to anyone. Not even each other. What will happen now?

I've chosen the evil mane six(or the mad six as I'll call them) from various grimdark fics.

Twilight: Twilight's dollhouse
Pinkie Pie: Cupcakes
Rainbow Dash: Rainbow factory
Rarity: The secret life of Rarity
Applejack: Bad apples
Fluttershy: Butterflies