I believe you can can find an UpGrade(used for evolving Porygon into Porygon2) in the Eterna City Hideout.
you have to get a porygon, then trade it with an upgrade, then you have to trade porygon2 with a dubious disc, which is found in the team galactic headquarters in veilstone city.
Trade Porygon with Up-Grade. This poses three problems. How to get Porygon, how to get an Up-Grade and trading. You can get Porygon in Veilstone City. Go to the house top-right of the Pokemon center. You get an Up-Grade on Route 224 and Eterna Galactic Building. Now you need to get a friend and trade or go onto the GTS.
If you have Action Replay DS, there is, you don't get the pokemon, but you have to full pokedex. You can also fill the pokedex if you have an R4 or are using a ROM, using Pokesav. From N.S.
In the wild or from professor oak
After defeating the elite 4 and obtaining the national dex, talk to prof. oak in eterna city. He'll give you an upgrade and talk about the birds. Then you can track them down with the poketch (they're roaming pokemon)
look for it in both team galactic buildings
Get the Upgrade from one of the Team Galactic Hideouts And then to make a Porygon Z get the Dubious disk from another one of ther hideouts
In Team Galactic building in Eterna City, in the chamber to the right after you've found the bicycle guy with Jupiter.
you have to get a porygon, then trade it with an upgrade, then you have to trade porygon2 with a dubious disc, which is found in the team galactic headquarters in veilstone city.
The Pokemon Platinum update for My Pokemon Ranch is only available in Japan for Japanese games.
You have to buy Pokemon Platinum. (Its a separate game!)
you have to have a upgrade and then trade it
You can't yet. Sorry.
go to oaks house after national dex complete
The Pokemon is poregon 2 and you trade poregon wile it is holding a upgrade.
you give porygon the upgrade then trade it to get a porygon 2 then you give your porygon 2 another upgrade and trade yet again to get a porygon-z
You must have seen all pokemon in the game then go to the lab in sandgem town. oak will appear and upgrade your pokedex.