>>31709358Tiers used by Smogon, which has their own competitive Pokémon meta. Smogon sorts Pokémon into different tiers depending on how many people use them.
Uber - The only tier above OU. It contains the absolute strongest Pokémon, such as the box legends like Mewtwo, Groudon and Xerneas (the only exception is Mega Rayquaza, which got its own tier, AG - Anything Goes, due to how strong it is.)
OU - Overused, the main tier. Contains the strongest and most used Pokémon, generally. Pokémon considered too strong for OU go into Ubers. Some OU Pokémon are Landorus-T, Mega Metagross, Toxapex and Tapu Lele.
UU - Underused. The tier below OU. Pokémon that aren't used that often fall into this tier. If a Pokémon receives lots of usage in a certain tier, you're not allowed to use it in any tiers below. This means that you have tiers were almost any Pokémon can be useful, even if it's weak, because stronger Pokémon will be unable to be used. Aside from tiering Pokémon based on usage, a Pokémon can also be banned from a tier if it's deemed too strong relative to the other Pokémon in the tier.
BL - Borderline. This tier is in-between OU and UU. Pokémon that aren't used enough to be considered OU, but were banned from UU from being too strong reside here. Examples include Staraptor and Mega Charizard Y.
RU - Rarely Used, The tier below UU. Pokémon that aren't used enough to be considered UU fall here. There's another Borderline, BL2, between UU and RU, with Pokémon too strong for RU that aren't used often in UU.
NU - Never Used, the tier below RU. Has its own borderline with RU, BL3.
PU - The tier below NU, contains Pokémon not used enough for NU. The name refers to PU, what'd you say when you smell something bad (as in, Pokémon in PU are so bad they're complete shit)
FU - A tier below PU, for even weaker Pokémon.
Another well-known tier is Little Cup, for Pokémon that can evolve and can be obtained at Level 5.
