Metallic Pokémon are one of the rare variants of Pokémon in Pokémon Vortex. Metallic Pokémon have 25% more defense than Normal Pokémon.
They were made by the staff of Pokémon Vortex. Hence, they are not to be used on any site other than pokemon-vortex.com. Example:
This Metallic Munchlax is a different color. However, you cannot catch a Metallic evolved Pokémon, as all evolved Pokémon can only be caught in the Normal Variant. Metallic Legendary Pokémon, however, can be caught.