Wooper is a mostly blue, amphibious Pokémon that resembles an upright, armless axolotl. Wooper's head is large compared to its body, and it has small, round, black eyes. It has purple, branching gills on either side of its head; the males have more branches in its gills than the females. Wooper stands on two small, round feet, and it has a large, thick tail. On its belly are dark blue curved markings.

It is implied in the anime that Wooper is a dull-witted Pokémon oblivious to its surroundings. Wooper lives in cold water most of the time. When sleeping, it partially buries itself in the mud at the bottom. It will occasionally leave the water when the air cools in the evening to search for food along the shore. While walking on land, it coats its body with a slimy, toxic film that keeps its skin from dehydrating and insulates against the cold. The film causes a shooting pain if touched barehanded. It is a timid Pokémon and tends to stay close to Quagsire. Arbok is a natural predator of Wooper.

Forms

Wooper has a regional form: Paldean Wooper.

Wooper in the Paldea region has a brown coloration, with two pairs of bone-shaped gills branching from its head, as well as an eight-pronged pattern on its stomach. Paldean Wooper once lived in the water during ancient times until they were forced out of their territory. As a result, they gradually adapted to living on land, namely in marshes. Paldean Wooper employs two adaptations to allow it to survive on land: its gills have hardened, and it coats its body with a poisonous film that keeps it from drying out. However, these adaptations resulted in Paldean Wooper having heavy bodies and being only able to move really slowly. To defend itself, Paldean Wooper can use its gills to unleash a powerful poisonous liquid. Paldean Wooper travel and work together in groups of three or four, and enlist the help of their evolutionary relative, Clodsire, to ferry them across water. Despite the adaptational change, Paldean Wooper can still float or swim in the water.

Evolution

Wooper evolves into Quagsire.

Paldean Wooper evolves into Clodsire.

(Source: Bulbapedia)