I've been looking at the credits for Friendship Games, since they didn't show off all of the main characters in the opening sequence after all, and in case you were looking for who voiced the Shadowbolts, I've got a list right here:

Sienna Bohn as Sugarcoat.

Sharon Alexander as Sour Sweet.

Kelly Sheridan (Also did Starlight Glimmer, Sassy Saddles, and Misty Fly in Friendship is Magic) as Indigo Zap.

Britt Irvin (Also did Lightning Dust in Wonderbolt Academy) as Sunny Flare.

And lastly, Shannon Chan-Kent (Known for Singing Pinkie Pie and Silver Spoon) as Lemon Zest.

4739746
Man, I was close to posting this!
Kelly Sheridan again, huh? She also did the Architecture Pony from Canterlot Botique.

4739746 Kelly Sheridan is doing a lot here lately - seems like Starlight is going to stay after the S5 finale, it wouldn't make sense otherwise.
Soon she'll have all the ponies to herself.
All of them.