Gansan is a pile of three octagonal, brown, big rocks with black, Kirby-like eyes on the upper one.
Gansan attacks its enemies by rolling towards them. Gansan rolls faster when rolling down a slope. Its eyes transition from one rock segment to another when it moves (its eyes will keep shifting to the upper-most rock). It gives the Stone ability when it is inhaled.
Gansan's name is derived from Japanese gan ("circle") plus san ("three"), referring to how Gansan consists of three circular rocks.