Welcome to the BW OU Viability Ranking thread. This thread contains a ranking of every viable Pokemon, separated in tiers to indicate power gaps. You may notice that they are not ranked alphabetically within their own subtiers; that is because every Pokemon is ranked within their subranks too. For example, if Garchomp and Keldeo are both S rank, but Garchomp is ranked higher than Keldeo, then Garchomp is the better one of the two.
Keep in mind that rankings are subjective and that your opinion is not a fact, but rather, you should use facts to support your opinions.
BW2 OU Ranking tier list V5
I made too many changes to list from the old thread to list them all, so feel free to contest anything. The most pressing issues right now: Landorus-T and/or Jirachi up to S? Everything's up for grabs. Go nuts :D