Porygon2

Porygon2 (ポリゴン２ Porygon2) is a -type Pokémon and is the evolved form of Porygon. It evolves when you trade it while holding an Up-Grade. Porygon will not evolve in Pokémon Green, Pokémon Yellow, Pokémon Red or Pokémon Blue. Porygon 2 can also evolve in the same manner into a Porygon-Z, which is only obtainable by trade, while holding the Dubious Disk item.

Appearance
Porygon2 is a duck-like Pokemon with large eyes and a blue duckbill and blue legs and tail.

Trivia

 * Porygon2 is the only Generation II Pokémon to never appear in the anime, as well as the only pre-Generation IV Pokémon to not appear in the anime or the movies, not even as a cameo. Popular opinion is that this is because of the incident involving its pre-evolution, Porygon, despite the fact that Porygon has made several cameos. It did, however, appear in the Johto Pokérap, though it was only stockart.