Hey everyone, Smogon moderator Arcticblast here. Make yourselves comfortable, because this might get long.
Note: This post is not intended to offend anybody, and if it does offend you feel free to contact me here, on Smogon, or on Pokemon Showdown. I usually hang out in the Strategy room (when I'm online) because the lobby is a headache to moderate...
It all starts with one tier: the standard tier. Initially, the banlist consists mostly (if not entirely) of Pokemon deemed powerful beyond a shadow of doubt. These Pokemon are all on Nintendo's standard banlist, although Smogon's differs in that Chatot and certain event legendaries are permitted. The event legendaries are allowed because we aren't taking availability into account, unlike Nintendo - if someone misses a Celebi distribution, they'd be at a disadvantage if Celebi was allowed in VGC, but on Smogon we use simulators so it doesn't matter. Once this initial banlist is set up, we have our standard metagame - OverUsed. Ubers is provided as an alternate playstyle where nothing is banned for those who want to use Pokemon such as Kyogre or Mewtwo.
Once this initial banlist is made, the metagame might be nice, but since Game Freak balances the game for VGC and Smogon uses 6v6 Singles, it's not perfect. In fact, there might be a lot of things wrong with it. First, global bans such as Evasion Clause (no Double Team garbage - note that Ubers removed this one), OHKO Clause (30% chance to lose one of your Pokemon guaranteed and there isn't a thing you can do about it? No thanks.), Sleep Clause (Do you really want all of your Pokemon asleep while your opponent sets up a SmashPass?). These clauses are put in place not because they are inherently impossible to stop, but because their presence results in a metagame that is unhealthy and uncompetitive. Once the standard clauses are laid down, attention is focused on the Pokemon themselves. In many cases, it's obvious what's wrong - Blaziken's combination of high-power STAB moves, Swords Dance, and Speed Boost made it incredibly difficult to stop. Landorus-I's Sheer Force set put a massive strain on teambuilding, requiring checks that often stacked weaknesses and threw off team synergy. Genesect was just ridiculous - it had every coverage move it could ever need, was able to get away from its counters with U-Turn, could exploit a Pokemon's stat distribution with Download, and so on and so forth. It's literally the biggest threat that's ever made it into BW2 OU - it literally had one hard counter in Rotom-Heat, and even its "checks" were probably weak to one of its common moves. The ban on Drizzle + Swift Swim on the same team was and still is a highly controversial ban. In this case, there wasn't one Pokemon that was the problem (except perhaps Drizzle Politoed, but that's a whole different can of worms) - it was just about every Swift Swim user in the game. They were incredibly fast and had their main offensive type boosted to insane power levels by the Rain. The options were initially as follows: Put a flat ban on Swift Swim, soft-banning several Pokemon that didn't have their DW abilities out yet; ban every problematic Swift Swim user, which would probably take at least a year on its own; or ban Drizzle outright, which would have removed several effective playstyles from the metagame and rendered some Pokemon unviable. Then the Drizzle + Swift Swim ban was proposed - a ban that would not only remove the problem entirely, but save the many playstyles focused on Rain and countless Pokemon.
And so we have our constantly evolving OU metagame. What about the other tiers though? Simple - they're just there for fun. Smogon's tiers are based on usage. If a Pokemon is not used in OU to the point that you are unlikely to see it at least once in twenty battles, it falls into UnderUsed. UU is simply a metagame where the Pokemon common in OU are completely absent - kind of a giant "what if we couldn't use those good Pokemon?" thing. That doesn't mean you can't use a UU Pokemon in OU, of course - OU allows the use of all Pokemon that aren't in the Ubers tier. UU has the same banlist as OU, but with the common Pokemon of OU banned (as well as a few other Pokemon that are deemed broken in UU). The other low tiers (RU, NU, and the unofficial PU) follow suit in a similar manner. Pokemon aren't placed in tiers because of how good we at Smogon think they are, they're placed in tiers because that's how everyone playing the tiers thinks that's how good they are, and uses the Pokemon they deem good and doesn't use the Pokemon they deem poor. Pokemon all the way down in NU aren't always bad in OU, of course - Stoutland, Sawsbuck and Scolipede are all viable in OU, for example. That's just where they ended up because people didn't use them enough in the higher tiers.
I hope I've been able to clear up some misconceptions as to Smogon's tiering system. If you have any questions about it, Smogon has a few articles on the matter, and I'm always willing to help out.
Note: This post is not intended to offend anybody, and if it does offend you feel free to contact me here, on Smogon, or on Pokemon Showdown. I usually hang out in the Strategy room (when I'm online) because the lobby is a headache to moderate...
It all starts with one tier: the standard tier. Initially, the banlist consists mostly (if not entirely) of Pokemon deemed powerful beyond a shadow of doubt. These Pokemon are all on Nintendo's standard banlist, although Smogon's differs in that Chatot and certain event legendaries are permitted. The event legendaries are allowed because we aren't taking availability into account, unlike Nintendo - if someone misses a Celebi distribution, they'd be at a disadvantage if Celebi was allowed in VGC, but on Smogon we use simulators so it doesn't matter. Once this initial banlist is set up, we have our standard metagame - OverUsed. Ubers is provided as an alternate playstyle where nothing is banned for those who want to use Pokemon such as Kyogre or Mewtwo.
Once this initial banlist is made, the metagame might be nice, but since Game Freak balances the game for VGC and Smogon uses 6v6 Singles, it's not perfect. In fact, there might be a lot of things wrong with it. First, global bans such as Evasion Clause (no Double Team garbage - note that Ubers removed this one), OHKO Clause (30% chance to lose one of your Pokemon guaranteed and there isn't a thing you can do about it? No thanks.), Sleep Clause (Do you really want all of your Pokemon asleep while your opponent sets up a SmashPass?). These clauses are put in place not because they are inherently impossible to stop, but because their presence results in a metagame that is unhealthy and uncompetitive. Once the standard clauses are laid down, attention is focused on the Pokemon themselves. In many cases, it's obvious what's wrong - Blaziken's combination of high-power STAB moves, Swords Dance, and Speed Boost made it incredibly difficult to stop. Landorus-I's Sheer Force set put a massive strain on teambuilding, requiring checks that often stacked weaknesses and threw off team synergy. Genesect was just ridiculous - it had every coverage move it could ever need, was able to get away from its counters with U-Turn, could exploit a Pokemon's stat distribution with Download, and so on and so forth. It's literally the biggest threat that's ever made it into BW2 OU - it literally had one hard counter in Rotom-Heat, and even its "checks" were probably weak to one of its common moves. The ban on Drizzle + Swift Swim on the same team was and still is a highly controversial ban. In this case, there wasn't one Pokemon that was the problem (except perhaps Drizzle Politoed, but that's a whole different can of worms) - it was just about every Swift Swim user in the game. They were incredibly fast and had their main offensive type boosted to insane power levels by the Rain. The options were initially as follows: Put a flat ban on Swift Swim, soft-banning several Pokemon that didn't have their DW abilities out yet; ban every problematic Swift Swim user, which would probably take at least a year on its own; or ban Drizzle outright, which would have removed several effective playstyles from the metagame and rendered some Pokemon unviable. Then the Drizzle + Swift Swim ban was proposed - a ban that would not only remove the problem entirely, but save the many playstyles focused on Rain and countless Pokemon.
And so we have our constantly evolving OU metagame. What about the other tiers though? Simple - they're just there for fun. Smogon's tiers are based on usage. If a Pokemon is not used in OU to the point that you are unlikely to see it at least once in twenty battles, it falls into UnderUsed. UU is simply a metagame where the Pokemon common in OU are completely absent - kind of a giant "what if we couldn't use those good Pokemon?" thing. That doesn't mean you can't use a UU Pokemon in OU, of course - OU allows the use of all Pokemon that aren't in the Ubers tier. UU has the same banlist as OU, but with the common Pokemon of OU banned (as well as a few other Pokemon that are deemed broken in UU). The other low tiers (RU, NU, and the unofficial PU) follow suit in a similar manner. Pokemon aren't placed in tiers because of how good we at Smogon think they are, they're placed in tiers because that's how everyone playing the tiers thinks that's how good they are, and uses the Pokemon they deem good and doesn't use the Pokemon they deem poor. Pokemon all the way down in NU aren't always bad in OU, of course - Stoutland, Sawsbuck and Scolipede are all viable in OU, for example. That's just where they ended up because people didn't use them enough in the higher tiers.
I hope I've been able to clear up some misconceptions as to Smogon's tiering system. If you have any questions about it, Smogon has a few articles on the matter, and I'm always willing to help out.
