A bit of random speculation/head-cannon that came to me today:
Snowflake (a.k.a. Roid Rage) has the same disability as Scootaloo. Bodybuilding isn't just his special talent, it's the only way he's able to generate enough power to fly with his tiny wings.
He might even be related to Scoots, a cousin, perhaps. That's how the CMC not only know him, but are on good enough terms to get him to help them train, despite the fact that he was clearly not thrilled about it.