(This will change right after we get a better one or I sit down to write a better one myself)
Forget story mode, forget catching, forget training, this one is a different game. Here we genetically modify pokemon just to do battle of the metagaming level and we like it. It's competitive battling.
We do it on two plus one places.
Pokemon Online is a downloadable pokemon battle simulator, which can be found here http://pokemon-online.eu/
If you are looking for quality it is pretty much the best one, and since it existed for a long time before pokemon showdown and was popular too, you will not have a hard time finding a match either.
Pokemon Showdown on the other hand is a browser based battle simulator. It does not require download. It is not without issues as it is still in beta, but there is not something significant enough to hinder the battling experience. It does have a lot of popularity so you'll be getting a battle anytime and it's always one browser window away. If you are looking for something quick, this is the one. It can be accessed here
http://pokemonshowdown.com/
The other way to play is through your traditional nintendo ds wifi battling, if you really have to go the extra mile.
In either case for the battle simulators all you have to do is get in, and like you would do with a deck of cards on dn, pick your pokemon, their EV and IV spread, nature, ability, moveset and held item (and gender, nickname, shiny etc. I guess). If you have to complain about people not catching their pokemon and cuddling with them and making love to them to help them in battle, just treat this as a different game entirely and spare everyone the meaningless protests. As a sidenote, on pokemon showdown, when teambuilding you get the exclusive pokemon of the tier you are building in appear first, showing you what the most viable ones are, while you will be given a list of the most viable moves, and hence strategies, when selecting the moveset. After having selected a moveset, an EV spread as well as a nature will be suggested to you, to help you with building your team if you are not yet into it.
If either you just don't know how to build a team yet and you haven't found one to copy/randomly throw together, or just want a weird challenge, in the challenge cup you and your opponent are given a random team of pokemon, balanced out as much as possible with level scaling, to play with. It's a decent way to get right into it.
Among the games I've played I've found that pokemon battling is one that is on the extreme side of metagaming. What will give you the biggest edge in battle and what will most of the times decide who wins and who loses in battle, is predictions. And to do that you need to be metagaming, which means you have to know what people are running and how they are doing it, you need to be able to get some decent guesses about their very EV spreads, most used abilities, movesets and strategies.
A player who does not know the game may try to set up calm minds against a cloyster thinking he is safe because he has resistances only to have that cloyster pull the trademark Shell Smash and proceeding to sweep his entire team, or may Toxic himself by trying to do so on a Magic Bounce Espeon, and so on, and so on.
In the case both players are aware it becomes a game of strategy and luck, where every move is part of the process of creating the conditions to win, and if both strategies are sound, prediction accuracy and the input of the random generator, with things like critical hits, move accuracy, status chances etc. being the deciding factor.
While of course, aside from in-game predictions, in team building, knowledge of not just what the most viable strategies to use for yourself are, but what main threats you have to prepare for and how, are what will make you at the basic level win or lose.
Of course some pokemon are just better than others, and if we are talking about metagaming then in this case it would be an over-centralized one and one with pokemon being very frequently in a team. To help with the fact that some pokemon just suck and some pokemon are just too good, the game has tiers to let players enjoy a lot of parts of the pokemon spectrum.
- Tiers:
The strongest ones play in Ubers. It's where you'll find the classic Mewtwo and the god Arceus and the rest of the stronger legendaries along with some which have just been banned from use on any lower tiers because they were just that good, like Sand Rush Excadrill. This is not the main tier, and that's because even though it has the largest number of pokemon allowed technically, it has the narrowest list of viable pokemon out of all tiers as you would imagine. It wouldn't be strange, and it would actually be common for half the team in a battle to be the same between the two players even if they do not employ the same strategy at all. Ubers is where things are banned, so you may say it is like our Traditional Format, however that is not to say the Ubers metagame is unbalanced or uninteresting. On the contrary, it is a very interesting metagame to explore where strategy still plays as big a part. And to top it off, it's of course enjoyable to have those huge powerhouses battle once in a while.
The OU tier, which is short for Over Used, is the main tier in competitive battling. It's where you'll find the most players, the main metagame and the strongest non-uber strategies. The release of any new pokemon game, new generation or not, new viable event pokemon and even new viable dream world pokemon releases with their new abilities, as well as usage statistics which make the tier changes, will shift this metagame often.
In the UU tier, which is short for Under Used, overused pokemon which either make up the strategies of the OU metagame, are just good in it or are simply too used in the UU tier and abuse it, are banned. With the tiers established, things are banned and unbanned in tiers mainly from usage statistics, meaning the least used of OU have a chance to be unbanned in the UU, while the most used of the UU have a chance of being banned from the tier, and this applies to all tiers below. Some strategies may be the best, but if you want to play without them, the second best is UU.
You can say that the RU tier, which is short for Rarely Used, is the UU of UU. The main pokemon of UU are banned in this tier, and the bans change in the same way that they do in UU. The next best and the next tier of viable pokemon to play with.
NU, which is short for Never Used, is the lowest official tier (there is an under-tier called PU though, which is not recognized as one however), with the main pokemon of RU banned, to be able to enjoy the next tier of pokemon.
There are other metagames in pokemon, like the Little Cup, Doubles, Triples and Rotation, even things like Create a Pokemon, but they are simply different metagames and irrelevant to the main usage.
If it's about studying up on pokemon battling, smogon university is the place http://www.smogon.com/
with articles http://www.smogon.com/bw/articles/
the strategy pokedex http://www.smogon.com/bw/pokemon/ with not only the tier listing of pokemon and main information (base stats, movepool, abilities), but also viable builds, strategies and even counters to them, for each (well, most) pokemon
and if you are willing to do more searching, the forums http://www.smogon.com/forums/ is where all of the things happen
Aside from a small random margin which is into every attack, damage is calculable beforehand if you can guess (which in most cases it is possible more or less) your opponent's defensive investment (EVs and nature boosts, etc.), or offensive if you are the defender, so you can use a damage calculator to help you make sure if your attack will kill the opponent or how many hits it will take to do so, or how many hits you can take from your opponent, to adjust your strategy accordingly. The one I prefer to use is this one http://kalashnikov.pokecenter.ru/damage/
Pokemon has the one of the best youtube community/support I have ever seen in a competitive game, with new battles available regularly, and with move to move commentary. Personally I was watching battles regularly a long time before I started doing them myself because I enjoyed them. There are many great channels in the community I have found and am following, but I will just link to pokemoshpit here, and most of them can be found by youtubing around https://www.youtube.com/user/PokeMoshPit/
This is my hastily thrown together Pokemon - Teach to open the section. I may as well end up being the only one using it, but I'm fine with that I guess. Any of you though, if you have anything to ask, bring up or discuss about competitive pokemon battling, don't hesitate to start a new topic in this section.