Late with this one. But this had RD written all over it. Enjoy the cover!

Applejack - Alto 2 (Lowest part)
*Bass line
Twilight Sparkle - Alto 1 (Second Lowest Part)
*Percussion and a second alto in some points
Rainbow Dash - Soprano 2 B (Third Lowest Part)
*Lead Vocals
Pinkie Pie - Soprano 2 A (Third Highest Part)
*Guitar
Rarity - Soprano 1 B (Second Highest Part)
*High Melody
And Fluttershy - Soprano 1 A (Highest Part)
*High Melody