The dubious disc is to be used with a Porygon 2. First, you must have obtained the porygon. To get a porygon 2, you trade a porygon to someone with it holding an upgrade from Silph Co., and then trade it back again with the dubious disc to get Porygon Z.
you Trade a porygon2 while holding Dubious Disc. you Trade a porygon2 while holding Dubious Disc.
It can be used to evolve a porygon2 when equipped and traded
go to survival area there will be a poké ball if you seek it then its dubious disc
Trade it while it is holding a Dubious Disc.
you find the dubious disc somewhere on route 225. good luck! you find the dubious disc somewhere on route 225. good luck!
it evolves porygon into prygon z and the up grade evolves it into porygon 2
go to route 225
A dubious disc is a hold item for Porygon2. If you trade a Porygon2 that's holding a dubious disc, it will evolve into Porygon-Z.
The Pokemon that uses the Dubious disk is Porygon2 to evolve him into a porygon-Z
give porygon (or possibly porygon 2) dubious disc ( i think you nick it from galactic hq) and trade him.
It evolves porygon2 (trade)
You find the Dubius Disc in the P2-Labratory in pokemon white. Hope that helped :)