She is voiced by Kelly Sheridan.
Indigo Zap is a student at Crystal Prep Academy. She's ultra-competitive, similar to Rainbow Dash. Unfortunately, she seems to think teamwork and peer pressure go hand-in-hand. When Sci-Twi became Midnight Sparkle, Indigo ended up having to help out some of her rivals from falling into a huge portal leading to Equestria.
The reason for not being present with the rest of the Shadow 5 and the Rainbooms during Dance Magic is because she was away on vacation.