Big Guy the Stilted is a giant robotic Shy Guy on Stilts operated by multiple Shy Guys in Yoshi's Island DS. He is the boss of his castle, residing there along with many Shy Guys. To defeat him, Yoshi must use eggs (or Baby Bowser's fire breath) to knock Big Guy the Stilted off the edge of the platform they are fighting on, which is surrounded by lava, giving the Yoshi a chance to ground-pound him. Many Shy Guys are inside this robot, jumping out occasionally making for an easy egg supply. After three Ground Pounds, it cracks, exposing all of the Shy Guy operators, after which it falls into the lava.
Big Guy the Stilted may have been planned to be a real Shy Guy instead of being a robot, as a pre-release image of it shows it almost devoid of the patches and robotic features that covered it in the final game. However, one patch is discreetly visible even in this screenshot, indicating that the reason for his lack of robotic features in the screenshot may have simply been because his sprite was incomplete at the time the screenshot was taken.
This is the only boss in Yoshi's Island DS that Kamek doesn't enlarge with magic.
This is the only boss you can fight with Baby Bowser (excluding Bowser) meaning he is the only boss you don't need to use eggs to beat.
He was planned to be a real Shy Guy rather than a robot.