Although I probably won't be voting in this suspect test, I'm going to comment on one aspect of Carracosta and Barbaracle that I think really heightens its brokenness.
Anyone who's played PU by this point knows that Jumpluff + Barbaracle/Carracosta makes it incredibly easy to guarantee a sweep, and I agree that it's pretty overwhelming on its own. But another aspect of the metagame that's super helpful to Barb/Costa besides Jumpluff is the fact that PU has a lot of other offensive sweepers that synergize ridiculously well with them and do a great job carving up teams that are "prepared" for them. My favorite example is Rock Polish Regice: it absolutely shits on the scarfers trying to check Barb/Costa (for example, Scarf Simipour does ~30% max with Hydro Pump), and tears through every Grass-type in the tier with its Ice-type STAB. It can be walled by dedicated special walls, but most of them are in turn utter setup fodder for Barb/Costa themselves. Fraxure is another very able sweeper that easily takes advantage of the plethora of Pokemon frequently locked into moves that might prevent Barb/Costa from setting up, such as Simipour, Raichu, and Floatzel, and it can put enough pressure on defensive Grass-types with Poison Jab that it can be difficult for them to come back in afterwards and stop Barb/Costa from sweeping. It's also got Dual Chop to mess with Kadabra if it really wants to. But where it gets really suckish for the opponent is that even if Fraxure's running Outrage instead, Kadabra still has to "choose" between RKing Fraxure or Barb/Costa. Once its Focus Sash is used up, Kadabra just becomes dead weight against a boosted Barb/Costa.
These are just two of the best examples, but PU's got a few other viable set-up sweepers that can function in a similar way and provide valuable support to Barb/Costa, so it's not at all hard to incorporate this kind of strategy into a team.
The real kicker is that ALL of these Pokemon can set up really easily with Jumpluff's support, not just Barb/Costa. Say Barb/Costa is forced out early somehow and you lose them? No worries, your backup sweeper will have an easy time setting up, and likely an easy time sweeping if Barb/Costa already got in a hit or two before going down. Get off an early-game Sleep Powder? Take advantage of it with your secondary sweeper while keeping Jumpluff and Barb/Costa alive and well in the reserve. The basic point is, Barbaracle and Carracosta have a lot of options for helpful offensive teammates, and many of them fare quite well against the few things that can actually pressure or stop Barb/Costa. And this isn't even taking into account the fact that Roselia/Piloswine are godly at both guaranteeing hazards and fulfilling their other important roles, and that powerful wallbreakers like Dodrio, Ursaring, and Stoutland are plentiful and very easy to fit on a team.
It's probably pretty obvious to anyone reading this that I am leaning towards pro-ban right now. And while there hasn't been much pro/anti-ban debate yet, I guess another thing I'm trying to say is that for anyone who might disagree that Barbaracle and Carracosta are powerful enough on their own to warrant a ban, their individual power is only half of the story. Looking at them from the context of the metagame as a whole, they're in what is likely the most optimal metagame for them ever right now, with a solid support partner in Jumpluff, a dynamic between hazard-layers and hazard-removers that strongly favors the presence of hazards, very capable wallbreakers, and offensive partners that can easily take advantage of each others' shortcomings. In other words, I'm seeing that the metagame is enabling Barbaracle and Carracosta to be extremely effective at what they do to the point that it's hard to justify running anything else because it's just so damn effective.
