Special textures

Several Pokémon have unique textures only available to them, in addition to their normal and Shiny textures. These textures are obtained through special methods.

Halloween starter Pokémon evolutions

The final evolutions of starter Pokémon (except for Chesnaught, Delphox, and Greninja) are able to take on Halloween-themed appearances. In order to obtain one of these special textures, several conditions must first be met.

If all of these conditions are true, using a jack o'lantern on the Pokémon will convert it into its Halloween special texture.

The Spectral Jeweller (Haunter)

If a player was one of the winners of the Halloween 2014 contest on the Pixelmon forums, the /redeem command can apply a special texture to an owned Haunter to take on the appearance of the Spectral Jeweller.

Roasted Magikarp/Zombie Gyarados

When a Magikarp is struck by lightning, it will turn into a roasted Magikarp. If a roasted Magikarp is then evolved, the resulting Gyarados will be a zombie Gyarados.

A regular Gyarados cannot be turned into zombie Gyarados directly, even when struck by lightning.