They are divided into servant class (miners) who do not wish to fight Autobots and are employed in mining for Energon, and warrior class, several are sent with nearly every Decepticon mission.Vehicons, or Eradicons, are drones who serve as foot soldiers for the Decepticons. The standard disguise for the soldiers are mostly purple muscle cars for ground operations. But air attack units have fighter craft alternate forms for air and space operations.
Starscream always wanted to be leader, but he found them not being able to agree with his speeches that he was superior enough to lead Decepticons into victory even when Megatron was gone. Starscream didn't care for the Vehicons as he emptied one of the Vehicons of his energon to test the Energon Harvester.
Starscream even slapped one of them in Sick Mind to shut up.
Airachnid, during the best was apart from the primary crew on the Nemesis also has Vehicons as henchmen.