Ulevo, I am surprised that you support banning Drizzle, because it seems to contradict with your stance of only banning broken things. Granted the fact that Sand and Sun would be broken without Rain was a legitimate concern, but the primary reason for Aldaron's Proposal was to remove the broken part, which was the terrible synergy of the abilities Drizzle + Swift Swim.
There is nothing officially determined, but I think the popular consensus is to initially ban 670+ BST Ubers. I'm interested to hear your suggestion ;d
I'm on my iPhone, so excuse typos.
My position leans towards banning Drizzle under the absence of the Drizzle + Swift Swim complex ban. I do not feel complex bans should be used as an option as I expressed earlier, and thus this would necessitate an alternative solution; to ban Drizzle.
Also, at the time of the proposal, the community was not properly informed or aware of the implications of their choices available. Everyone just assumed that if we solve the issue surrounding Swift Swim users in rain, Drizzle and the rain playstyle would be balanced, or at least manageable. The majority did not consider that rain would be broken even without Swift Swim, and this is understandable given how early the game was in its life cycle and how chaotic the tier was for a while with Darkrai, Shaymin-S, and Deoxys-A running around.
That being said, while I don't have the BW2 experience to give direct input as to whether Drizzle now in its current state would warrant a suspect test or ban, the fact that some do believe so, and that we have had to ban several Pokemon who thrive under rain as a prominent condition (Manaphy, Tornadus-T, Thunderus) as well as currently suspecting another (Keldeo) where their status may have otherwise been proven to be OU if Drizzle was not legal is evidence enough for me to consider what the real culprit is.
So within my context, I believe Drizzle is likely broken. I believe it has played a significant role in other suspects being banned while it has remained untouched due to favouritism, even after Swift Swim was a non-factor (which as I stated shouldn't have been a consideration.)
EDIT: Moving on to my suggestion for the initial ruleset for X & Y.
I believe having the majority of 670+ BST Ubers banned from the start is the best for time efficiency, particularly since we will no longer have Japan only initial releases, and we will have much less time to properly analyze Pokemon before they hit the simulators to determine how we might tier them. While this list might be up for some debate, the obvious include Arceus, Dialga, Giratina, Giratina-O, Groudon, Ho-Oh, Kyogre, Kyurem-B, Kyurem-W, Lugia, Mewtwo, Palkia, Raquaza, Reshiram, Zekrom, and any newly introduced titled legendaries.
I added all the foreseen here for simplicity. Obviously there are specific cases that would be debated
based on previous generation experience like currently legal Kyurem-B, but because of their innate base powers I think testing them in a more stable environment with semi-experienced Gen VI players would yield better results for properly tiering them.
Pokemon like the previously legal Blaziken, Darkrai, Deoxys, Deoxys-A, Deoxys-D, Deoxys-S, Excadrill, Genesect, Landorus, Manaphy, Shaymin-S, Thunderus, and Tornadus-T should be legalized. While some of these are extreme cases, like Shaymin-S, Darkrai, and especially the volatile Deoxys-A, most of them could be considered OU under the right conditions. Blaziken might not have access to Speed Boost initially, and there might be ways of handling it in Gen VI, while Manaphy might not have access to Drizzle initially to exacerbate its advantages. Some of these might just go through Latios/Latias syndrome and become less of a threat in Gen VI with new tools on how to handle them, or becoming outdated and obsolete due to power creep.
For the clauses, I advocate we remove the Swift Swim + Drizzle clause, not just for the sake of assessing the conditions of a new generation and setting a proper precedent on complex bans, but to allow us a chance to properly tier Drizzle by its own merit. We should carry over our rule to ban Sand Veil and Snow Cloak if it means that we won't innately ban any Pokemon unjustly from the get go. Soul Dew should likely be banned as usual, and I don't really see a reason to unban Moody either as it falls under the stipulations of evasion.
We take a 3 month period where no suspect tests take place, and we only resort to emergency tests or bans under extreme and blatantly obvious cases (i.e. Moody) while we let the meta set in. After 3 months, we nominate who we feel should be tested and proceed with the routine suspect tests.