It evolves into Ninjask starting at level 20. Additionally, if the player has a spare slot in the party and an extra Poké Ball, a Shedinja will appear in the player's party when Nincada evolves. An extra Poké Ball is not necessary to obtain Shedinja in Generation III.
Nincada is a small, whitish, insectoid Pokémon. It has a pointed snout, a thin stripe that dips in a V-shaped pattern between its eyes, and two whisker-like antennae on its face. Its eyes are black with green iris-like rings inside. As it is virtually blind, it uses its antennae to sense its surroundings. On its back is a pair of small, green wings. Its hind legs are white, but the forelegs are brown and have sharp claws.
The claws are used to carve into the roots of trees and absorb moisture and nutrients. Nincada builds underground nests at the roots of trees in tropical and temperate forests. It can occasionally live up to 10 years underground. It does not like sunlight, so it avoids it. Nincada is nearly blind due to living almost entirely underground, as such, it uses its antennae to see instead.
Nincada is the only Pokémon to have a higher base stat total than its evolved form, as it has 30 more base stat points than Shedinja.
Nincada is the only Pokémon to have a gender, be able to learn TM moves, but not to learn Attract or Captivate. This is possibly to prevent Shedinja from knowing these moves due to being gender unknown.
Nincada is exclusively in the BugEgg Group, but Shedinja is exclusively in the Mineral Egg Group. These two are the only evolutionarily-related Pokémon to not share identical Egg Groups, excluding those that transition in or out of the No Eggs Discovered Egg Group.
Nincada is a combination of ninja and cicada. Its association with ninjas may be inspired by stories of ninjas using cicadas to mask their own sounds, or a reference to the utsusemi no jutsu (cicada skin technique), a technique using decoys to misdirect opponents.
Tutinin is a combination of 土に埋める tsuchiniumeru (to bury in the ground) and ninja.