It evolves Porygon 2 into Porygon Z when held and traded. Consider yourself lucky, I can't seem to find the Disc.
What Does The Dubious Disk Do In Pokemon Soul Silver?
You'll be needing Rock Climb, then go to Mt. Mortar.... From there on :
www.psypokes.com
That will come in handy...
www.psypokes.com
That will come in handy...