Although technically a virtual, manmade Pokémon, Porygon-Z does have a physical body. Its head is fuchsia and ovoid in shape with a short, blunt antenna protruding upwards and a blue bill similar to that of a duck. Its eyes are yellow and have black rings, similar to a bulls-eye. The head is completely detached from the body and floats slightly above it. Its smooth, ovoid body is fuchsia with a blue ring connecting its arms. Two arms are loosely connected to its upper body and other than their blue color, have no features. The tail is also blue and featureless, but slightly resembles a paddle.
Porygon-Z was given additional software in order to increase its abilities. The initial idea was to give it the ability to travel through alien dimensions, but an error occurred. Instead, the Pokémon began acting erratically. Porygon-Z, and its pre-evolutions are the only known Pokémon that can learn Conversion and Conversion 2.
In the anime
Porygon-Z in "World of Pokemon"
Porygon-Z's only appearance in the anime was a cameo in the "World of Pokémon" opening of Kyurem VS. The Sword of Justice, in which every Pokémon from the first five generations (apart from Genesect) appeared. As was the case with Porygon2, it is currently believed that Porygon-Z will not properly appear and will not be mentioned in the anime as a result of the EP038 incident, although the release of official anime artwork for Porygon-Z suggests that it was considered to appear.
Porygon-Z's pre-evolutions have their own signature Conversion move, but no new Conversion-style move was made for Porygon-Z.
Since no leveling up is required to evolve either Porygon or Porygon2, Porygon-Z is the only Pokémon that can evolve twice while still being level 1. Roserade is another fully evolved three-stage Pokémon that can be at level 1, but only if it starts out as Roselia instead of Budew.
Porygon-Z is the only Pokémon that evolves from a Pokémon that evolves via trading while holding an item. It is also the only Pokémon who evolves from a Pokémon who already evolved from methods other than leveling up (not including evolutionary lines where baby Pokémon are the first stage).
Although it has never made an anime appearance, Porygon-Z had anime artwork made for it.
Origin
Like Porygon and Porygon2, it is based on a bird made with 3D computer graphics. Its appearance with respect to Porygon2, as well as its unprogrammed behaviors, suggest that it may be based on the concept of a computer virus having infected Porygon2, or maybe a reference to copyrighted software usually being patched by users to use all the features, but often causing bugs in the program.
Name origin
Porygon-Z is a combination of polygon and Z. It may also reflect the stereotype that Japanese people pronounce their 'L' sounds as 'R' sounds, Porygon being a mispronunciation of polygon. Z may refer to the Z axis in 3D coordination systems or that Porygon-Z is the last of its evolutionary line (since the letter Z is last in the Latin alphabet). Alternatively, Z may be a corruption of 2 (as in Porygon2).