I could average deuce anywhere with a urethane Black Hammer, as long as I had some 320, 600 and 1000 grit sandpaper, and access to a good Lustre King machine. That's all anyone needs. However, to be competitive with such a limited arsenal, you would need to be EXTREMELY accurate, master about 3 different releases, and have the speed control of Walter Ray Williams. It can be done, but why make life difficult? It isn't that much hassle to lug around a 3 ball roller and a 2-ball tote.
If I was limited by rules, I could survive with a 3 ball arsenal. I would take my polished Warp Zone, my tame drilled Time zone, and probably force a Power Groove to do double duty as a light oil and spare ball.