.:You're a Disaster:.

Starlight Glimmer gets a reading from Starshine Bright, learning that she is a calamity in and of herself.
Starshine is less than pleased to see the pony.

This was done to be a title card for my thoughts about Starlight Glimmer, in particular her "necessity" to the Royal Problem as an episode.
To summarize, no she isn't necessary for the episode to work and it could have been accomplished by Twilight and AJ, or Twilight and Flutters, or many other ponies just as easily. I don't hate her, but she's a discount Sunset Shimmer and I'm tired of her being shoe horned into the series so much, quite frankly Twilight is the main character and she doesn't need to be supplanting her role this much.