Porygon evolves into Porygon-2 when traded while holding the item "Up-Grade".
the upgrade is used to evolve porygon into porygon-z
Use the dubious disk to evolve Porygon or Porygon2 to Porygon Z
You will have to evolve a Porygon. By evolving it you have to trade it while it is holding an Up-Grade.
Porygon does not evolve at a given level: you have to trade it while it is holding the Up-Grade to evolve into Porygon2. Then trade that while holding the Dubious Disk to get a PorygonZ.
It is used to evolve Proygon2 into Porygon-z.
Trade it while it is holding a Dubious Disc.
You can give the Upgrade to Porygon and then trade it to a friend to make Porygon evolve into Porygon2, in order to evolve Porygon2 then give a Dubious Disc to Porygon2 and then trade it to someone and it'll evolve into a Porygon-Z.
Eevee can not evolve into porygon.
Porygon 2 and porygon- z
You use it on a porygon and it will evolve.(Pokemon Diamond, Platinum, and Pearl only.
Porygon can evolve into Porygon 2, while holding an Upgrade and traded. Even further, Porygon 2 can evolve into Porygon Z, while holding a Dubious Disc and traded.
In Pokemon Platinum (I don't know about Diamond and Pearl), Porygon is located in a house directly behind the Pokemon Center. If you want to evolve into Porygon 2, trade it holding a Up-Grade, and if you want to evolve Porygon 2 into Porygon Z, trade it holding a Dubious Disk. I do not know where htese items are found. If you want to get Porygon the harder way, use Pokecheck.