As you might guess from the name, Overkill is all about excess. Sometimes this works to his advantage, such as when his endless tirades and theatrics distract his foes in combat. Sometimes excess works to his disadvantage, such as when he gets so caught up in showing off that he becomes distracted in combat. And sometimes it just makes him look silly, swinging and blasting at a fallen foe long after the fight has ended.
Though he talks a better game than he fights, Overkill's dinosaur mode is strong enough to be a decent threat... except when the circuits that control his size-change from cassette to dinosaur malfunction (as they are wont to do) and he finds himself stuck as an audiotape-sized dino. Awwww!
His alt-mode is a Ceratosaurus/Microcassette.