From Wicked, the hit Broadway musical, Nightmare Moon, Twilight Sparkle, and the Citizens of Ponyville all sing Idina Menzel's Act I finale, "Defying Gravity" in a small story about Nightmare Moon defying her sister Princess Celestia [The Wizard].

Characters:

Nightmare Moon: Elphaba
Twilight Sparkle: Galinda/Glinda
Princess Celestia: The Wonderful Wizard of Oz
Everyone Else: The Citizens of Oz

Note: There is a stifling amount of repeated clips, I know, but that is due to the incredibly limited amount of footage of Princess Luna/Nightmare Moon. Please pardon this.