Think of these as Pokemon ranking systems, with Uber being the highest and NU being the lowest (there is also FU and PU but those aren't official tiers). The most well known tiers that 99% of players use come from Smogon.com, who regularly update and change them if need be. There are five official Smogon tiers, which are Ubers, OU, UU, RU and NU.
Basically, each Pokemon is given a tier based on their usage in battles. Tiers are separate metagames - for example, if you played an OU battle, you would not be allowed to use Pokemon in Ubers as they are banned from OU. Similarly, if you played NU, any Pokemon ranked in RU, UU, OU or Ubers would not be allowed. OU is the tier that is most similar to wifi battles, as all the broken legendaries and over-centralising Pokemon get banned to Ubers.
A Pokemon changing its tier can happen two ways - either through a suspect test or due to usage. A suspect test is when Smogon identifies a Pokemon or a group of Pokemon that are too strong in the tier they are placed in. Once a suspect test is started, players compete in the tier, and once they achieve a certain rank on the ladder, they may vote for a ban or no ban.For example, they are currently suspect testing Draglage, Serperior and Pidgeotite in RU. Dragalge and Serperior both recently got powerful Hidden Abilities, and Pidgeot-Mega is without a doubt one of the best Mega Pokemon in the tier. The suspect test isn't done yet, but based on discussions in the Smogon forums, at least Dragagle and Serperior look like they will be booted from RU and placed in the tier above, UU. A Pokemon can also move due to usage - if a Pokemon achieves a usage of roughly 3.4% per battle in the tier above it, it will automatically move to that tier. Similarly, if a Pokemon drops below 3.4% in its tier, it will drop down to the tier below.
The Pokemon tiers are as follows:
- Uber - self-explanatory; all the best Pokemon in the game reside here, including most of the overpowered cover legendaries.
- Overused (OU) - the most popular tier that is the most similar to wifi battles, except with a few more Pokemon banned.
- Underused (UU) - everything that isn't good enough for OU but too good for the lower tiers is placed here.
- Rarelyused (RU) - Pokemon that aren't the worst but aren't particularly good are placed here.
- Neverused (NU) - the lowest of them all, where all the worst Pokemon are.
These are many, many different styles of teams in the games, but there are three that are particularly dominant in each tier.
- Balance: these teams are a mix of different Pokemon with different roles that work well together. Common structures for balance teams include several offensive Pokemon and one or two defensive Pokemon that can take hits and counter attackers that threaten other members. Type synergy (how well you can cover each Pokemon in the tier and its attacks with your team) is particularly important with this, as this play style often involves a lot of switching and prediction.
- Hyper offence: the aim of this strategy is to use almost all attackers in the team, and overwhelm the opponent with them. Quite often type synergy is dropped in favour of coverage and the ability to beat walls and opposing hyper offensce teams effectively. Hyper offence teams can use bulky attackers, speedy revenge killers, and more - there are many variant ions of it as there are with the other two main types of teams.
- Stall: these teams often use multiple Pokemon with defensive capabilities that intend to wear down attackers with status conditions, entry hazards, etc. whilst taking as little damage as possible. Stall is a more difficult playstyle as teambuilding options are more limited, and being able to answer every offensive Pokemon in the tier is difficult - however, when done correctly, stall is extremely threatening, particularly in the higher parts of the ladder against players who know what they're doing. Stall teams often include some offensive Pokemon that can break through opposing stall teams or bulky Pokemon that may be difficult to take down otherwise.
As stated before, there are so many others to factor in along with those, including weather-based teams, Trick Room teams, etc. these three are just the most common, and most teams can be called at least one of them.
Roles (sweeper, attacker, wall, support, pivot etc.)
As with teams, there are many different variations in roles, but most Pokemon can be called either an offensive Pokemon, a defensive Pokemon or a mixture of both (generally called a "tank"). Pokemon that are predominantly offensive can be called attackers or sweepers, who intend to break through teams with power or sweep teams using set-up moves.
Walls and support Pokemon are ones that are there to sponge hits and use offensive Pokemon that can't beat them as a way to set up. Support Pokemon often carry a way to heal HP, set-up moves like Stealth Rock, a way to apply status to a Pokemon (often with Thunder Wave or Toxic which many Pokemon can learn) and usually an offensive move to avoid being Taunt fodder and to be able to deal some damage. Walls are often described as "passive" since they aren't capable of doing much damage, but the support they provide for teams can win battles. Be careful with how you play with them though, as you may end up allowing your opponent to set up.
Other roles include revenge killers (who use Choice Scarf usually), or pivots who act as a glue to take a hit, force a switch and then switch out often with U-Turn or Volt Switch which puts you in control of the game. There are so many other purposes that Pokemon have, but most are either defensive or offensive or a mixture of both as stated before.
Where do I battle?
You can play competitive games over Wifi, but battle simulators are much more accessible, fast and offer quality opponents that Wifi does not. It also allows you to type out a team rather than spending a month breeding in-game for it. By far the best battle sim our there is Pokemon Showdown, which uses Smogon tiers and rules and is the most pleasing to the eye. Just Google "Pokemon showdown" and you'll find it.
What formats are there?
Competitive games are usually played in singles, however there has been a separate metagame for doubles for many years, and more recently, Smogon triples became available. Singles are by far the most played format, but if that's not your style, you can play doubles or triples (the triples community is still young though).
There's also the VCG format, which is the one that the Pokemon Company use when holding official tournaments. It's in doubles as well, but it has different rules from the Smogon doubles.
Some tips/ recommendations
- Don't be disheartened when you get thrashed to begin with - many people have played competitive for years and have much more experience than you do. Your teams and your battles will be bad at first, but you will improve eventually.
- Practise makes perfect. Keep playing, keep making and testing new teams and practising prediction.
- Learn the Pokemon in the tier and what they do. This will give you a better idea of how to counter a Pokemon.
- Read articles, read teams, watch videos, etc. and learn from them. While you will learn the most by playing the game, often seeing how other people play is a good way to get started. I highly recommend youtube.com/PokeaimMD. He uploads competitive battling videos, explains why he makes certain moves and does teambuilding sessions, and should help you out a lot. If you want to read stuff, go to Smogon,com and read stuff like their viability rankings and their analysises for each Pokemon if you're ever in need of a move set.
Leave a comment if you have any more questions, I know how confusing my writing is. Also, I had a section for the rules and clauses, but I hit the character limit so yeah (I typed too much wow).