Sneasler is a bipedal Pokémon that resembles both a cat and a weasel. Its body is dark gray with purple accents around its face and ankles. Its fur is longer on its shoulders. It has long arms that extend to just above its ankles. On each arm is a dark spot, and its hands have three long claws tipped with poison, which are black with three red lines streaking through. Like its pre-evolved form, it has sharp, narrow eyes with red pupils and black markings resembling eyelashes on the edges. It has yellow diamond-shaped gems on its chest and head, and three sharp toes on each foot. Its left ear has a long black and red feather that extends down to its back; it also has red and black feathers for a tail.
Sneasler's evolution was the result of Hisuian Sneasel adapting to life on cliffsides in the frozen highlands of Hisui. Despite Sneasler's lanky build, it possesses great strength owing to its vicious claws. Due to its severe poison and deadly physical power, no other Pokémon species could defeat Sneasler in its habitat. Using its claws, Sneasler is capable of climbing up walls and cliffs with ease. Unlike its counterpart, Weavile, it prefers to be alone instead of living in packs.
A special Sneasler is worshiped in Hisui due to her being descended from one of the 10 ancient Pokémon who received a blessing from Arceus. In particular, she is one of the Ride Pokémon who resides in Coronet Highlands and assists humans.
Sneasler is the only known Pokémon capable of learning the move Dire Claw.
- Sneasler and its pre-evolution were designed by Hitoshi Ariga.
- Before Sneasler was officially revealed, a silhouette of it climbing a mountain was leaked months prior to the game's release.
- In Pokémon Legends: Arceus's internal code, Sneasler did not have Unburden as an Ability.
Sneasler may be based on weasels and the kamaitachi, weasel yōkai with sickles on their front legs. However, its humanoid appearance and Poison-type may be based on another yōkai, the ōnyūdō (lit. "big monk"), who take on the appearance of monks and are said to afflict illness to anyone who sees it. There are stories of animals that can shapeshift into ōnyūdō, one of which being the weasel. It also shares some traits with cats.
Sneasler may also be based on a free climber or a ninja. Its claws and signature move could be based on the tekkō-kagi, metal hooks with multiple protrusions in the shape of a claw equipped by ninjas for climbing and assassination. Its Poison type may then refer to the ninja's skills in poisoning.
Sneasler may be a combination of Sneasel and ruler. It could also be a combination of Sneasel and the comparative suffix -er, meaning more (thus "more Sneasel", alluding to it being physically similar to Hisuian Sneasel apart from its larger size).
Ohnyula may be a combination of 大 ō (big) or 大入道 ōnyūdō (big monk) and ニューラ Nyula (Sneasel).