Developed to supplement marine mobile suits with heavy firepower during amphibious attacks, as well as to provide a tough and durable weapons platform for underwater combat, the Grabro carries on the fear and intimidation that has become a hallmark of Zeon's mobile armor program.

The Grabro's primary armament are a set of seven-tube torpedo launchers mounted directly behind its advanced sonar dome "nose" section. Various sizes and payloads allow the Grabro to effectively deal with both enemy surface warships and other aquatic targets. As with anything underwater, it is vulnerable to attack from above, so the Grabro is equipped with a set of surface-to-air antiaircraft missile launchers. They take off vertically, similar to a miniturized version of the Mad Angler's long-range boomer missiles. Three claws, usually used as maneuvering surfaces but quite capable of hack-and-slash attacks, are mounted on each of its "arm" appendages.

One of the Grabro's finest features are its gigantic "arm" devices. These multi-jointed appendates are flexible and can move in virtually any direction, allowing it to direct thrust from its hydrojets virtually anywhere. This gives the Grabro unprescedented maneuverability that even eclipses marine mobile suits in underwater combat.