This will be updated as I have more ideas, or suggestions. After reading Bulbapedia [sic], I disagree. Porygon2
It's not 'Porygon Two,' it's 'Porygon Squared.' They couldn't do this in the Gen. II games and it's just stuck, like having two different species of Nidoran. Think about what it evolves into: Porygon-Z. Three-Dimensional. Cubed. One step up from Squared.
Dunsparce
Based on the Tsuchinoko? Erm, no; it's based on cave-dwelling creatures that never see the light of day and are therefore pale with no eyes. Harrumph.