Robo-Crab

 is General Pig and General Sheep's secret weapon and ultimate battle robot. It's the final boss for Act 3, and is fought at Crab Claw Cove while being operated by the pirate generals.

Abilities
Its size is weapon enough, complete with mighty pincers, sharp legs, and even a flight mode that comes with a tractor beam.

Trivia

 * The Robo-Crab was actually created by General Monkey.
 * The Robo-Crab boss fight references plenty of robot and Sci Fi shows, and even the infamous Giant Enemy Crab.