Stufful is a quadruped Pokémon resembling a bear cub. Its body and head are mostly pink, while its legs are brown. Each foot has a single pink paw pad on the bottom. There is a white, semicircle marking around its face similar to a headband, and it has a white muzzle with a triangular, black nose. Its white-tipped ears are situated on the sides of its head, and there is a small, white-tipped tuft of fur under each. Around the center of its short, puffy tail is a dark pink ring marking. Under the tail is a small, white flap resembling the tag on a stuffed toy. This is actually an organ that releases an odor used to communicate with others of its kind. Stufful is very small and ties with Mankey as the smallestFighting-type.
Despite its small size, Stufful has extraordinary strength and can knock out even well-trained Pokémon if they are unprepared. The combination of its cute appearance, mannerisms, and fluffy fur make it very popular. However, Stufful actually dislikes being touched and will flail its powerful arms if it is embraced. Stufful's flailing is powerful enough to break thick tree trunks.
A Trainer's Stufful appeared in League Offenders and Defenders!. Team Rocket encountered it and mistook it for Bewear's child, therefore believing its presence to be a sign of Bewear being on her way to take them home. However, their concerns were assuaged when they saw Stufful's Trainer.