Onslaught is what you'd call the "hands-off" type. He doesn't enjoy getting his mitts dirty, but instead prefers the thrill of designing battle plans, strategies, and tactics, and then watching his Combaticon soldiers carry them out. While he typically crafts his strategies to exclude his direct involvement, Onslaught is no coward. When required, he will engage in battle with strength, cunning and earthquaking fury. This darker, more brutish side of Onslaught might lead some Decepticons into thinking he has a secret blood-lust stashed away in his circuits. But truth be told, he's really just ticked off that his plans didn't work out the way they were supposed to.
Onslaught can combine with his fellow Combaticons to form Bruticus, who is considerably dumber than Onslaught.
After his conversion to Power Core Combination technology, he took the code name Combatmaster.
His alt-mode is a Anti-Aircraft Truck.