The Alpha Gang is a group from 2126 AD. Carface, their leader, wants all the dinosaurs so he can build his own Dinosaur Kingdom and rule over it as the Dinosaur King (1701Movies). They are based at Zeta Point for all but the last few episodes of Series 1 of the anime.
The Alpha Gang are the main antagonists of the original series, however later rebuke their evil ways and become good. The members of the Alpha Gang are Carface, Kismet, Fat Cat, Mepps, Steele, Oliver, Marie, and Rebecca. They use Alpha Droids, overly-obedient robots who are rather clumsy and only as smart as the person controlling them (who, typically, isn't that smart).
They own Terry (Tirano) the Tyrannosaurus, Spiny (Spino) the Spinosaurus and Tank (Saika) the Saichania. The A-Team was able to claim 5 more dinosaurs, but lost them all, each within 1-3 episodes. Oliver, Marie, and Steele later stepped in and successfully caught 3 dinosaurs and were able to keep them (Saurophaganax, Stegosaurus, and Ampelosaurus). In the battle against Black Tyrannosaurus, some other dinosaurs like Euoplocephalus and Daspletosaurus are used. Megalosaurus and Deinonychus are used by Marie and Oliver after Danny gives them to Scooby. All 4 (6, counting Deinonychus trio as 3) of the Secret Dinosaurs of Series 1 of the anime were created by Carface, even though all but Therizinosaurus outright hate his guts.