I know it would be crazy, but who knows? It may be fun...

By that, do you mean complete the Unova Dex only as close as possible on one save file without trading or connecting to another game? That's sounds extremely long. But go for it if you want. The Unova Dex in B2W2 has about 390 Pokemon (including the Pokemon you have to choose from, such as the starters)

I was just thinking that it would be a feat that only the strongest of wills can beat. Hopefully I can see if I can try it out, just to test myself.