BattleBorn had a great idea today of perhaps organizing a Pokemon tournament using the site play.pokemonshowdown.com; however, I noticed that a lot of people in the comments don't really know how the tournament-style set up works. That's perfectly understandable, I only learned myself a few months ago when I discovered the site. I'm going to do a very brief guide on the basics of high-level play to help you guys out. Anything I've missed, feel free to add and correct in the comments.
There are currently 6 main tiers in the Pokemon metagame: Little Cup, Neverused, Rarelyused, Underused, Overused, and Uber. Most of the people use the latter 5, as Little Cup is more of a niche tournament style. The tiers work like this: a Pokemon in their tier can play in any of the ones above it, but none of the ones below it. For instance, Kingler is in NU, so it can challenge any Pokemon in the 4 tiers above it. Lugia is in Ubers, so it can only fight in Ubers, as that is the highest tier. Pokemon are sorted by their stats and move pools. Kingler may have a catastrophic 130 base attack and a respectable 115 base defense, but its restrictive move pool, low speed, HP, and special stats leave it a very niche Pokemon, leaving it in NU. Most pokemon in the game are in NU, and OU is the most popular tier. OU is pretty much any pokemon minus the more powerful legendaries, Excadrill, and Blaziken.
2. EV stats
EV stats sound confusing, but they are quite simple. I'm not going over how to EV train, but only what the levels do. Basically, a Pokemon has a total of 510 usable EV points. You gain EV points in certain stats by battling certain Pokemon. This is why two level 100 Kinglers may be very different in terms of power. One may have higher defenses, while the other has a higher speed. Basically, every 4 EV points gives you 1 point into the stat you want. The most efficient way to do this, and pretty much the only thing you will see in tournament play, is to put 252 EVs in two stats, and give the remaining 4 to one other. Kingler has very hard-hitting physical attacks, but is very frail; what you would want to do is put 252 EVs into attack to increase its physical force, 252 in speed to help with moving first, and the remaining 4 in HP to give it the tiniest touch of extra HP.
3. Entry Hazards
Entry hazards are a force to be reckoned with in Pokemon battles. I'm referring to the moves Stealth Rock, Spikes, and Toxic Spikes. Basically, if you get an opportunity to drop these hazards on another team, they will take damage every time they switch. If an opponent stacks 3 spikes, some toxic spikes and a stealth rock, depending on its type, a Pokemon could lose up to 75% of its HP simply by switching in and also be poisoned. Also, these traps ruin very important items like focus sash, which only works when you Pokemon are at full HP. The Pokemon that use these hazards are usually very sturdy tanks with high defenses and HP.
Each Pokemon on your team needs to fulfill a certain role. Some of the roles are physical sweeper, special sweeper, tanks, trappers, and healers. Sweepers are your damage dealers. Most of the time, they are armed with a life orb to give their moves 30% more damage at the cost of 10% of their max HP per turn. They are able to knock out most pokemon in one hit, and are usually dealt with by using a faster sweeper, a status effect, or an eject move like whirlwind. Tanks are meant to take tons of damage; they usually carry status effect moves, enrty hazards, and a healing move. Some Pokemon, like Ninetails and Politoed, are used to set up weather conditions during a match. I like to use a drought team, meaning my team works best in sunny conditions.
5. Revenge Killing
Revenge killing is the act of taking advantage of having your pokemon faint by throwing out an incredibly fast pokemon that can knock out the killer in one hit. Scizor is an example of this. It can use an item like choice scarf to increase its speed by 50% at the expense of only being able to use the first move it picks. It also has a move called pursuit which does extra damage to switching pokemon.
Items are the bread and butter of your team. If you don't use the correct items, your team will most likely fail. Research is usually required to know which item is best for your Pokemon's role, but you'll quickly see trends starting to form once you look at it.
So I think I've at least covered the basics. Anything else you can learn by going to http://www.smogon.com/. Thanks for reading, and I hope it helps you out. Don't be intimidated! Let's get this tournament rolling!
EDIT: Also, I'll be free most of the week if anyone wants to practice their teams against me.