Banette is a dark gray, doll-like Pokémon that is possessed by pure hatred. It has three short spikes on its head and a long zigzagging ribbon trailing off the back of its head. A zipper acts as its mouth, and it has purplish-pink eyes with slit pupils. Its long, flat arms have three-fingered hands, while its legs are short and stubby. It has a yellow, brush-like tail.
As Mega Banette, this Pokémon gains several additional zippers: one running diagonally across its face, one on each hand, and another on its body. The first zipper runs from its left eye to the tip of its central spike. The other three are all unzipped, revealing parts of Mega Banette's cursed purple body. Its three long purple fingers and body revealing two pointed, purple legs are visible. Its zigzagging ribbon becomes somewhat erect, and now has two zipper rings around it and a short zipper on the tip. It gains four further spikes: one on the top and bottom of each hand and one on each hip. However, it loses its brush-like tail.
Being driven to life by a powerful grudge, it keeps its life force safely in its body by the means of its zipped up mouth. If unzipped, it would lose its energy. It lays curses on others by using its body as a voodoo doll and sticking pins into itself. It lives in garbage dumps and dark alleys, where it searches for the person that threw it away before it became a Pokémon. It is said that treating it with enough care will satisfy its grudge and will turn it back into a stuffed toy. When it Mega Evolves, it is filled with so much power and vindictiveness it cannot help cursing its Trainer.
Banette can be seen as a parallel to Dusclops. Both are Generation III Ghost-type Pokémon that evolve from their pre-evolved forms at level 37. Both also have the same base stat total. Wild Banette are exclusive to Pokémon Sapphire, while wild Dusclops are exclusive to Pokémon Ruby.
However, with the introduction of Dusknoir in Generation IV and Mega Banette in Generation VI, the similarities between the two evolutionary lines have become less notable, as Dusknoir has yet to receive a Mega Evolution and Banette cannot evolve.
Despite Banette's zipper needing to stay closed in order to conserve energy, Banette's Pokémon-Amie animation shows it unzipping and opening its mouth in order to smile or eat.
Banette seems to be based on the idea of a haunted doll, while its Pokédex backstory of an ordinary doll coming to life is similar to the tsukumogami, an idea rooted in Shinto's animism. Its appearance and habit of sticking itself with pins is also a reference to the popular concept of a voodoo doll.