I can see Porygon getting as many evolutions as Eevee, actually.
The Porygon family tree:
......-----> Porygon-V --("Dark Disc")--> Nogyrop?.....
.... /......
...("Damaged Disc")...
..../.......
Porygon----> Porygon2----> Porygon-Z......
....\.......
...("Sturdy Disc")......
.....\......
......-----> Porygon.2 --("Unbreakable Disk")--> Porygon.3....
NOTE: Ignore the dots. I just put then in there to align everything. :F
Middle Line: The line line that goes straigth down the middle, is the Sweeper Porygon line, the one that's already been created.
Line That Goes Up: The line that goes up, is the Annoyer line. The "Damaged Disk" is an Upgrade disk that was damaged. You give it to Porygon, expecting a Porygon2, then the Disc damages Porygon's molecular sctructure, turning it into Porygon-V (Virus). Next, if you give it the "Dark Disc" it will turn into an Evil Virus Pokemon, hense, Porygon spelled backwards. :F Nogyrop would use moves like Leech Seed, Hypnosis, Thunderbolt, Taunt, Snatch, Thunder Wave, WoW, Toxic, etc.
Line That Goes Down: The line that goes down, is the defensive Wall line. You give a Porygon a "Sturdy Disc", then, it evolves into Porygon.2 (POINT 2!). Next, you give it the Unbreakable Disc, turning it into Porygon.3 (POINT 3!). It would use moves like Recover, Reflect, Light Screen, Stealth Rock/Spikes/Toxic Spikes, Protect, etc.
ANOTHER NOTE: ALL of these Porygon evolutions would be NORMAL types!!!! Thank you, that is all. :F
Oh, and, all three of the final forms would be in OU.