The NU list would be the UU list, but with all popular Pokemon cut out (no Steelix, Weezing, Claydol, Scyther, Rotom, Altaria, etc.). From there, we'd play NU matches and figure out which Pokemon are over-centralizing/over-used. Those Pokemon would be banned and we'd keep playing until, well, we have a playable metagame :p. Standard clauses would be in effect, although we can certainly discuss them and decide if any should be discarded/added. Stealth Rock MAY end up being banned. That will be a discussion for another day.
Sadly, to make this work, we really need a decent number of people. If I don't get enough replies, we can't really do this.