Well, Flash is quite the generic character so far. The way he was introduced makes it feel like he's nothing more than a jock love interest for Twilight. Not necessarily a bad thing, but there's nothing really likable about him compared to the Mane 6 and the immediate cast. If they decide to flesh out his character, give him more interactions with the cast and give him something unique to work with, then he could be quite the interesting pony. The potential is all there to be a core character instead of a high school crush shoe-in for the show.