From Bulbapedia, the community-driven Pokémon encyclopedia.
Tiers are an attempt by players to classify characters in a game by their competitive ability. They can be found in any game with variable characters, including Pokémon and Super Smash Bros. The existence of tiers can be controversial as skill usually has more impact on the outcome of a match.
Tiers in Pokémon
Pokémon features hundreds of species available for use, all varying in their base stats and moveset potential. There are currently six tiers with various fansites individually deciding the Pokémon assumed to be in those tiers, most notably Smogon and Pokémon Online. Pokémon tier lists have received much criticism, because there is no "official" tier list for Pokémon. However, official tournaments often have ban lists.
In "standard" battles, any Pokémon that is not in the Uber tier is eligible for use. However, it is common for some battles to maintain use in one tier only.
The Uber tier is effectively a banlist for OU, however this does not mean it is not, or cannot be used. Pokémon in the Uber tier are deemed too powerful or centralizing to be used fairly among other Pokémon.
It is a misconception that the Uber tier contains only legendary Pokémon. While it is true that a majority of Ubers are indeed legendary, not all Ubers are legendary, nor are all legendary Pokémon Ubers.
While most Pokémon in the Uber tier are there due to high stats, Wobbuffet is often classed as an Uber because of its Shadow Tag Ability, along with Encore, its high HP stat, Counter, and Mirror Coat; this lets it trap any opponent Pokémon and lock them into any move, so that the player knows what their opponent will do next, which allows the player to either switch out Wobbuffet knowing what the opponent will do, or use Counter or Mirror Coat to damage the opponent. Wobbuffet's pre-evolution, Wynaut, is also often banned for similar reasons. Wobbuffet is not usually Uber in Generation V tier lists.
Blaziken is often classed as an Uber because of its Speed Boost Hidden Ability, which when combined with Swords Dance, Blaziken becomes very powerful and faster than most opponents. Other non-legendary Pokémon such as Excadrill are considered Uber due to their movepools, high base stats, type, and Abilities. Conversely, Kyurem (in its normal and Black formes) is not considered Uber despite its very high base stat total and lack of a hindering Ability such as Slow Start, due to its Ice typing and comparatively small movepool limiting its options against other Pokémon.
Over-Used, commonly abbreviated as "OU", refers to Pokémon that are most commonly seen in standard play.
It is a misconception that all OU Pokémon are the most powerful in the game. OU is a term based on usage; however, there is a distinct correlation between usage and usefulness in the system. There are exceptions to this such as Magneton in Generation III, where it was considered an OU Pokémon solely because it was used as a counter for Skarmory, a commonly used Pokémon. Magnezone, the evolution of Magneton, took over its place in OU, due to increased stats and a broader movepool.
Pokémon in Borderline, commonly referred to as "BL", are considered by some to be too strong for Under-Used, but are not sufficiently used to be considered OU. It is effectively a ban list for Under-Used.
Under-Used, commonly referred to as "UU", designates Pokémon whose use is limited as they are not strong enough for general OU competition, usually due to sub-standard stats, movepools, easily exploitable weaknesses, or the existence of a stronger Pokémon that works in a highly similar way. For example, Machamp is in UU due to Conkeldurr having Mach Punch and better bulk. UU Pokémon can be, and are, used in OU battles, but are usually underpowered here.
Pokémon in Borderline 2, or "BL2", as it is more commonly known, are considered to be stronger for RU/LU. As such, it is a ban list of said tier.
These two tiers, commonly referred to as either "RU" or "LU" (the name depending on where the player is playing or what they are playing by), designate those who are not used enough in the Under-Used or Over-Used tiers to be considered either of them, or do not have the necessary stats or movepool to be Borderline or Borderline 2. For example, Nidoqueen is considered RU because Nidoking is often considered a better choice for UU battles. Several of the Pokémon in this tier are used in OU and UU battles, however, barely any, if any at all, are common in these tiers.
As the name implies, Never-Used, commonly referred to as "NU", is for Pokémon that have problems competing in RU/LU due to poor stats and/or movepools, and thus are extremely rare to be used in battles. This is where most novelty Pokémon reside in tiers as well as Pokémon found early in a player's journey. Many Pokémon that are pre-evolutions of Pokémon that are OU or Uber are also considered NU. They are generally only used in NU battles; however, some Pokémon such as Shedinja and Torterra are often classed as NU, but are often used in other tiers, most notably RU. Many NU Pokémon are common in Pokémon Contests and Pokémon Super Contests.
Not Fully Evolved
This tier is more commonly known as "NFE", and as the name implies, contains almost every Pokémon that has not yet reached its final evolution. It is a sub-tier of NU. Some NFE Pokémon, such as Rhydon are used in the lower tiers, as their stats are on par with some of the weaker evolved Pokémon. Also, the Abilities of Hippopotas and Snover are the only way to set up permanent weather in the lower tiers, as their evolved forms are banned.
- Main article: Little Cup
Little Cup is where only lowest evolutions are allowed, such as Bulbasaur and Timburr. Pokémon that do not evolve at all, such as Luvdisc, are not allowed in the tier, and some deemed too broken for Little Cup, such as Gligar, Carvanha, and Meditite are also banned from the tier. It follows the same rules as the Pokémon Colosseum and Pokémon Communication Club Colosseum special rule.
Some Pokémon are listed in tiers but are sometimes used in competitive play outside of their own tier because they have a change during evolution that modified their disposition enough to allow them to stay competitive, even some in an unevolved state.
- Porygon2, which is due to its evolution, Porygon-Z, having lower Defense and Special Defense, meaning Porygon2 can be used as a wall, while its evolution can not.
- Light Ball holding Pikachu are also due to the Light Ball doubling Pikachu's Attack and Special Attack stats, as well as Pikachu being a very common fan favorite.
- Magneton, as previously stated, is still used in lower tiers because it still carries the ability to trap Steel-types with Magnet Pull. It is also used because of its various resistances and high Special Attack. It also has some use in OU battles, as its slightly higher speed than Magnezone allows it to outspeed many OU Pokémon that Magnezone cannot.
- Eviolite, an item that multiplies both defenses of Not Fully Evolved Pokémon by 1.5, has made several other pre-evolutions—such as Gligar, Dusclops, Porygon2 and Chansey—popular in higher tiers, Dusclops even being in higher tiers than its evolution on some tier lists.