Unban everything after r2, just to see what happens. Also perhaps Manaphy.
I agree with Texas Cloverleaf here, we really don't know how the current ubers perform in Dream World OU. If you have to ban most of the stuff within a day or two, fine, but whatever stays will make the Dream World OU metagame more fun. Some things in particular I would like to see stay if this ever happens:
Lugia: This has been talked about in OU before, but never seriously considered. In DW, we have Tyranitar, ST Chandelure, Excadrill, Garchomp, and Thundurus, all of which are really not that good in Ubers. These Pokemon alone are enough to bring Lugia down. Lugia was never really tested in OU in the first place, so it would be interesting to see how it does as well.
Giratina-A: It's really bulky, yeah, but we have things like Choice Band Tyranitar, Lati@s, Haxorus, and ST Chandelure in DW OU to deal with it. Giratina-A would provide an unexplored prospect that was never really considered in OU.
Giratina-O: Dream World OU is no stranger to rain, which neuters any attempts for Giratina-O to beat steels. Ferrothorn, Gastrodon, ST Chandelure, and Tyranitar all deal with it as well.
Deoxys: Base 150 attacking stats along with base 150 speed is nothing to laugh about, but in DW Deoxys's problems with priority and Choice Scarfers can finally catch up to him. With Scizor and rain, along with Ferrothorn in rain, not to mention Tyranitar if it lacks Superpower, also Pursuit users, Deoxys can finally reach a place where it is amazing but not overtly so. Even if it does turn out to be really good, I just think it deserves a chance. If it turns out to be broken, I will have no qualms with a ban, but it definitely deserves the chance.
Drizzle + Swift Swim: With rain and sand, along with TechniLoom, Gastrodon, and Soul Dew for Lati@s, Drizzle + Swift Swim can be effectively stopped with skillful playing, a little prediction, and a safe switch to ST Chandelure on Politoed at low health. Drizzle + Swift Swim could be simply great but not broken in Dream World OU, and could be a great addition lost because of the OU banning process and no thoughts of unbanning.
If any of the things I listed above or anything else would get unbanned in the drop all process, we would be left with a better metagame because of it.