You can't find it from the wild, only trade it while it holding a Dubious Disc.
Porygon-Z is a Normal type pokemon.
porygon z is at the oil field hideout
it is in OIL field hideout
trophy garden (save in front of the door leading to the owner's office, talk to the owner, if he doesn't say there was a porygon in the trophy garden turn ds off and try again until he says porygon)
the upgrade is used to evolve porygon into porygon-z
Porygon-Z is #474 in the national pokedex, and it is a Normal type Pokemon.
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
Porygon-Z can breed with Porygon and Porygon2 (its earlier evolutions) when both are of opposite genders. However, Porygon-Z cannot breed with other Pokémon outside its evolutionary line.
To find porygon-z, just go to the oil field hidout and look there(never tried but saw before). P.S. he has very strong ability and life.
In the Pokemon mansion talk to Mr. Backlot and he will say some cute Pokemon gave him a smooch and if it is porygon run in the trophy garden to find one . You will have to trade it when it is holding the Upgrade . That is Porygon2 . Porygon Z you trade a Porygon2 When it is holding the Dubious Disk .
Porygon-Z
It evolves Porygon 2 into Porygon-Z when you trade Porygon 2 while it is holding the Dubious Disc.