Shelmet

Shelmet is a Bug-type Pokémon.

It evolves into Accelgor when traded for a Karrablast, which evolves into Escavalier simultaneously. Neither evolves if at least one holds an Everstone during the trade.

Biology
Shelmet is a bivalve or snail-like Pokémon. Its gray shell resembles a knight's visor, with a coiling spiral of its shell further back. The shell has protrusions on the underside, which it apparently uses as legs. Its inner body is pink with a long, puckered mouth, and green markings below its eyes.

It closes the lid on its helmet-like shell as a defensive tactic, and can spit a poisonous sticky fluid. However, this strategy doesn't work against its rival and natural predator Karrablast who can open Shelmet's shell. It can evolve around the time as its rival through electrical-like energy. It thrives in moist habitats like bogs and swamps.