get porygon up to a good level, then give the upgrade or dubious disc to porygon, then trade it and trade it back, if you give it upgrade, you will get porygon2, if you give it dubious disc, you get porygon-Z! yay!
you cannot evolve a porygon2 in leafgreen
You must evolve Porygon (From Celadon) using the UpGrade to Porygon 2.
You need to trade a Porygon holding an Upgrade.You get an Upgrade from Silph Co building.
you trade it while holding an up-grade.
Trade a Porygon to a friend while it holds the item Up Grade when it's traded it will evolve then ask for Porygon2 to get it.
you can't. dubious disc is to evolve porygon 2 into porygon z, porygon z is a sinnoh Pokemon and leaf green only goes up to hoeen
To evolve Porygon when it holds the item 'upgrade' and it is traded over to another game. It will evolve into Porygon2.
get the upgrade in the rocket warehouse on Five Island and then trade to another GBA game and then it will evolve. (porygon can be bought at lv. 18 at celadon game corner, and must be holding upgrade to evolve.)
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
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.