They are the evolutionary items for porygon.
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You find the dubious disc at the p2 laboratory on route 17-18. You find the upgrade on route 15, very close to white forest. You have to beat a Pokemon ranger and have strength to push a boulder and get to it.
The Pokemon that uses the Dubious disk is Porygon2 to evolve him into a porygon-Z
To evolve Porygon to Porygon2, you will need to have it hold an Upgrade and trade it. You can get Porygon-Z by having Porygon hold a Dubious Disk and trade it.
Cheat code of dubious disk is very long but really great so here it is 94005535 FFCF4232
It evolves Porygon into Porygonz.