Time for another tier update! For those new to our system, how our tiers work is that they're primarily based on usage (the names of the tiers, OU, UU, RU and NU, literally mean "Overused," "Underused," "Rarely Used" and "Never Used"): Pokemon that are used heavily in the tier above get banned from the tiers below. The cutoff for each tier is the point at which you're more than 50% likely to encounter that Pokemon at least once in a given day of playing, if you play 20 battles a day. For those that don't feel like doing the math themselves, that number is approximately 3.41%. So that means if a Pokemon is used on 4% of OU teams, it's considered OU and is banned from UU, RU and NU. This 3.41% number is based on stats weighted over the previous three months, with 5/6 of the weighting from the last month, 1/8 from the month before that, and 1/24 from the month before that (ratio of 20-3-1). Finally, for those who are familiar with how we calculate usage stats know, we weight our stats based on player skill rating, and we're calculating stats using a baseline of 1695 for OU and 1630 for UU, RU and NU. To eliminate some numerical anomalies, we're also throwing out teams where the player's RD is greater than 100 (meaning they've had less than ~5 battles under their alt). This decision is detailed in this thread. On top of the usage-based tiers we also have "borderline" or "BL" tiers, which are essentially Ubers banlists for the lower tiers. These lists ban Pokemon that aren't used enough in the higher tiers but are too overpowered for the lower ones. BL banlists are not subject to usage stats, except a BL Pokemon can, of course, move into a higher tier (from BL to OU, from BL2 to UU). Also note that a Pokemon cannot drop more than one tier per update cycle. Say no one used Charizard in OU for the next three months. That would drop it down to UU, even though it had no usage in UU for that period (how could it? It was OU). Further notes: suspect tests were included in the rankings wherever possible, with weight for that given tier and month being split proportional to the number of battles on each ladder. Example: say there were 10,000 OU battles in March vs. 5,000 OU Suspect battles. Then March's OU ladder would contribute 2/24 to the tiering and March's OU Suspect ladder would contribute 1/24.