Yeah, I know; that's what I'm predicting to be the case. My point at mentioning that was, while being extremely unlikely, it's possible that a Pokemon that's currently UU will end up being broken even in standard with DT, and thus be moved straight from UU to Ubers, which is another reason why a UU-only test of Double Team isn't optimal (which is what the person I was responding to was talking about; the idea of testing DT only in UU as the first part of the test). It's a very unlikely scenario, but a possible problem with the idea of only testing DT, and thus me pointing it out as a flaw in the idea. As you said though, such a scenario isn't likely, and if one or two Pokemon end up being broken with it in UU/OU, then they will be moved up to BL/Ubers.
DT will only be considered broken if a large number of pokemon become Uber when using the move, even if the pokemon was previously UU. Otherwise, the move itself wouldn't be broken, but rather the user. We give out less bans than more bans; that's why we ban Garchomp instead of Yache Berry, for Yache Berry is only broken when used on Garchomp or perhaps Rayquaza. But it's not broken if Salamence, Dragonite or Gliscor use it. So we do one ban on Garchomp instead of banning it on every pokemon, including three different pokemon that could use it.
It's like saying that if Registeel gains Recover, it ends up broken, and then we conclude that Recover is a broken move. But Starmie, Alakazam, Porygon-Z and every other use of Recover or a move that functions exactly the same as Recover (let's ignore Softboiled, Slack Off, Milk Drink, Roost, Moonlight, Synthesis, and Moonlight) are not broken with that move. It's just Registeel. What seems more broken, and what requires less bans - banning Registeel, or banning Recover on every pokemon.
From looking at the Bibarel set, it won't break UU - too many pokemon can wall it (Shaymin, Registeel, Spiritomb, even Roserade with Rest/Synthesis if he lacks Return). The only way Bibarel might break UU is with Baton Pass support. But then again, +3 (6) Atk and Speed Bibarel is also a complete menance, and he's still UU.
[EDIT]
In response to your post Relictivity, chances are that I will have something to 2HKO the Double Teamer. #2 pokemon in usage, Salamence, can OHKO or 2HKO every pokemon in OU with LO Outrage except Steels and Cresselia. Outrage, of course, has it's obvious problems, but Salamence could still 2HKO many ideal DT users with Draco Meteor and Fire Blast. Wallbreakers make an excellent DT counter. Other great pokemon for OHKOing or 2HKOing most DT users include Tyranitar, Infernape and Heatran. Or if I lack a pokemon capable of 2HKOing most of the metagame, I can rely on weaknesses to take down a Pokemon. Every good team will have Ice Beam for Gliscor. The only pokemon that might be problematic is Cresselia should I not have Tyranitar or Scizor, but she just finds it too hard to threaten a team after +6 evasion.
The only teams that might not 2HKO a DT user are Stall teams. However, if DT is allowed, Stall teams will make small adjustments that will allow them to deal with DT. Perish Song is an excellent example of a DT counter. It's most likely to be used on Celebi, who outspeeds or speedties with all the pokemon that would consider using DT. Those users who do speedtie with it (most likely other Celebi) cannot learn Taunt, and still won't be able to stop Perish Song. And perhaps most importantly, Perish Song is NOT affected by accuracy. Toxic Spikes on the field stops any DT user without an immunity to the move.
One more thing with Stall Teams - they will have an easy time PP draining DT users unless they have Baton Pass support. Name one bulky DT user that with +6 Evasion can sweep a stall team. If the team has Baton Pass, the team would defeat the team the same way it would defeat Baton Pass.
