Dewott is a bipedal, otter-like Pokémon that is primarily light blue. It has small black ears, a pointed crest at the back of its head, a red nose, and long white whiskers forming tilted V-shapes. Two pointed teeth are visible in the upper jaw when its mouth is open. Its forelimbs have three fingers on each black paw. Its feet and flat tail are black. Around its waist is a large, dark blue, fringed arrangement of fur, with two scalchops on the thighs.
Dewott's scalchops are detachable, and Dewott regularly trains to use techniques with them; these techniques differ between individual Dewott. It always maintains its scalchops as well. Its flowing double-scalchop techniques can defeat even those who master the art of swordsmanship. When exposed to the harsh environment of Hisui, Dewott gains an additional Dark-type when it evolves into Hisuian Samurott.
Dewott is based on a sea otter and samurai. Its trait of fighting with its two shells may be based on Tessenjutsu, a type of martial arts involving the Japanese war fan. Dewott's evolutionary line as a whole is based on the lifespan of a samurai: from a child (Oshawott), to a young samurai (Dewott), to a military commander (Samurott).
Servine, Pignite, and Dewott's evolutionary lines are collectively based on Western, Chinese, and Japanese culture respectively, to represent the diversity of the Unova region.
Dewott may be a combination of dew, water, and otter. It may also involve duel, dual (referring to the two scalchops it fights with), or duo (Italian for two, referring to its place in its evolutionary line). Notably, Helen DeWitt is the name of the author of The Last Samurai.
Futachimaru may be a combination of 二つ futatsu (two), 太刀 tachi (long sword), and 丸 maru (round; common suffix in male Japanese names).