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Welcome to the SM UU Viability Ranking Thread, brought to you once again by yours truly! In a similar fashion to how things were done throughout the course of the last generation, I've assembled a group of knowledgeable UU players to help me sort out the preliminary rankings. This group will also help me going through nominations made in this thread, as well as metagame shifts caused by drops and successful retests. The group in question is subject to change though, and they're not the only people whose opinion I'll be consulting frequently.
So where do you come in? After the preliminary rankings have been worked out by our team, it's the community's duty to refine them in order to more accurately reflect the true viability of all relevant Pokemon in the UU metagame. Because our guesses will come before much meaningful experience using Pokemon will have occurred, we can't be accurate enough without your help. Post about the Pokemon that you have experience with, but try not to let your personal bias oversell any Pokemon.
The S tier contains a select few metagame-defining Pokemon, the best of the best, and the A tiers reflect on the Pokemon which are extremely effective but flawed in some aspects. The B tier is slightly more expansive, with the B+ tier representing Pokemon that are fairly common and threatening but don't quite make the cut for A-, while the B- tier represents Pokemon who fill minor, but relevant, niches. Below the B tier, the generic C tier displays the rest of the Pokemon that are usable in UU, but don't have a niche that is appreciated by most UU teams. Finally, the D rank will only include Pokemon that are tiered in UU by usage, but have no usability in the metagame. Furthermore, discussion on D-ranked Pokemon is NOT ALLOWED in this thread.
The UU Viability Ranking Council will be the same as the UU tiering council for now, but as I've mentioned before, this is prone to being changed in the future.