according to 4chan, which is where these leaks came from, this confirms a couple things previously leaked a few months ago
there are spoilers ahead but since it's Equestria Girls i don't feel like hiding it
one of them being Brad, whose actual name is Flash Sentry. he tries to flirt with Twilight briefly in both worlds, but nothing happens past them dancing during the school prom and a couple hugs. it's not an "over-arching plot", more time is spent of Sunset Shimmer's story. sighs of relief can be made until after we watch the movie.
things are looking up in terms of the movie not interfering with Friendship is Magic. also, Celestia and Luna look so strange lol