Oshawott is a bipedal sea otter-like Pokémon. It has a spherical white head with small, triangular dark blue ears on the sides. Oshawott's eyes are black, and its dark orange nose is shaped like a horizontal oval. Several freckles cover its cheeks which may be premature whiskers, and two pointed teeth can be seen when it opens its mouth. The turquoise fur on its body forms bubble shapes around its neck. Its arms are white and rounded, while its feet are dark blue with three toes each. It also possesses a rudder-like dark blue tail. It carries a pale yellow seashell called a "scalchop" on its belly.

This shell is made of the same material as its claws and is used for both battles and cracking hard berries. Oshawott wields the shell like a knife. It uses the scalchop to block the moves of its enemies before slashing back at them in swift retaliation. Oshawott learned to how maintain its scalchop with riverbed stones by copying the humans it observes using whetstones. If the scalchop is heavily damaged or lost, Oshawott can grow a new one from its navel.

Oshawott has two main evolutions within the Pokémon franchise. The first is Dewott, which represents an intermediate stage: it becomes more agile, confident, and skilled in combat, using the shells attached to its arms as weapons with greater precision

The final evolution is Samurott, which takes on a very different form, resembling a large armored sea lion. In this phase, it is much more powerful and resilient, standing out for its strength and advanced battle techniques, while still retaining the use of shells as sharp swords.