When SB2 comes out will there be multiple tiers just like singles? I think there should be a ladder for normal 6v6 doubles and one for VGC style.
There should be two VGC ladders, one with 2010 rules, and one with 2009 rules, slightly altered. It seems with the release of Heart Gold and Sold Silver, there is some sort of auto level 50 for local wifi, which means they should allow Tyranitar and non TRU Dragonite. Also, the formes should be allowed, since in HG/SS they are obtainable by everyone.
The 4 vs 4 double battle has no issues with dark void. Only smeargle is able to learn it, and it is not overpowered at all. Dark Void smeargle is easily counterable. A lum berry or chest berry user is all that is needed to stop a dark void smeargle from destroying teams.
On the discussion of a sleep cause, I think there should be none inforced. In the double battle metagame, smeargle will be the only user of Dark Void (assuming Darkrai is in Ubers). A dark void smeargle is easliy stopped by a priority move + chesto/lum berry. Smeargle has frail defences and isn't hard to kill by any means.