The Scorpions were local gang of bullies and degenerates, the Anti-T-Birds, lead by Leo Balmudo.
Flashy cars, leather jackets, cigarettes, Marlon Brando lookalikes, leather hats, and sleazy girlfriends - that's the Scorpions. Leo and Cha-Cha were the primary members.
After Leo's defeat at Thunder Road, he lost his car to Danny Zuko, the Scorpions apparently disbanded, and Cha-Cha ditched Leo.
That wasn't the end of Leo and his gang, though; Now astride a motorcycle, He dredged up a replacement gang - the Cycle Lords.