Next to Galsia, Donovan is just about the most common and easily defeated enemy in the series, although Donovan does have one or two advantages over his comrade, such as a handy anti-air uppercut and a natty pair of shades. The former is nothing to be sniffed at given the effectiveness of jumping attacks in beat-em-ups, though Donovan doesn't use it often on lower difficulties.
While Galsia specialises in knives, Donovan is capable of using pipes, albeit rather slowly. In Streets of Rage 3, he is also able to steal exposed food items off of the ground to restore his health. He also once attempted to run the heroes over with a bulldozer, but was thwarted by the inconvenient placement of a metal girder and a steel can.
On higher difficulties this guy has an amazing anti-air uppercut, making it nearly useless to jump at him.