It evolves from Goomy starting at level 40 and evolves into Goodra starting at level 50 when leveled up during rain in the overworld. Rain instigated by Rain Dance or Drizzle will not trigger this evolution.
Sliggoo is a gooey purple Pokémon with the body structure of a snail. Its underbelly is a deeper shade of purple than the top part of its body. It is over twice as tall as its preevolved form, but remains relatively small. Its eyes are now green and large, with one eyelash on each eye; but since its eyes are devolved, Sliggoo is blind. It has two pale green spots on either side of its head. It has two small, underdeveloped arms, two sets of antennae atop its head, and a gooey snail-like shell on its back that looks like it is part of its gelatinous body.
Sliggoo, the Soft Tissue Pokémon. The evolved form of Goomy. Its four horns are a high-performance radar system. It can use them to sense sounds and smells.
Requiring 40 levels to evolve from Goomy and just 10 more to evolve into Goodra, Sliggoo has the lowest relative second-stage evolution requirement, at exactly 25%.
Origin
Sliggoo seems based on soft bodied gastropods such as slugs, nudibranch, and semi-slugs.
Its snail origins as well as its dragon typing and elongated body shape may mean it could also be based on the Lou Carcolh, a mythical serpent/mollusk creature from French folklore.
It may also be based upon the concept of "living slime" in popular culture.
Name origin
Sliggoo may be a combination of slick, slimy, slug, and goo.
Numeil is from 滑る numeru (to be slippery) and snail.
This Pokémon article is part of Project Pokédex, a Bulbapedia project that aims to write comprehensive articles on each Pokémon species, as well as Pokémon groups and forms.