Chesnaught is a bipedal, mammalian Pokémon with some plantlike features. There is fluffy white fur on its belly and fringing its face like a beard. It has a small, pink nose with a three-pointed patch of brown fur extending up its short snout and four pointed teeth. On top of its head is a plate of beige armor, similar to a helmet. It possesses a prominent domed, armor-like shell similar to that of a chestnut. The armor is beige with four large spines jutting out of the back. The armor is trimmed with red and green bands; the green is on the outermost edge. There is an additional spine protruding from the armor over each of Chesnaught's shoulders, which are connected by a green breastplate. Its body is colored similarly to the shell, and its long limbs and tail are banded with plates of armor. The top surfaces of the tail and arms are protected by green armor, and each arm has two small spines. It has three brown, clawed digits on its hands and feet. Its hands can fuse to create a spike-covered "shield".
Chesnaught is renowned for its tank-like body; it is capable of flipping a 50-ton truck. Once it gets into its defensive stance with its hands covering its face, it can stand up to a bomb's explosion. It will not hesitate to use its sturdy body to shield its allies from danger. While Chesnaught is normally gentle and prefers avoiding conflict, it will not hesitate to give opponents a thrashing with its thorned fists when the situation calls for it.
