Here, we call for a champ - the first person to respond when "new champ" is called by the previous one claims the position.
It is recommended that champs use a tripcode in order to prevent confusion.
Showderp viewers will then suggest any six Pokemon: the suggestions can be as vague as "your favorite RU Pokemon", or detailed down to EVs and moves. This is entirely up to the user's discretion.
Shitmons (such as Heal Pulse-only Slowbro and Black Sludge Shedinja) can be fun for a while, but they will usually serve as only dead weight on a team. We therefore recommend suggesting Pokémon that have a chance in OU.
The champ will take the first six Pokemon suggested, and with them, attempt to challenge the OU tier (sometimes Ubers or even LC) with his or her ragtag band of misfits.
After some battles, the champ may call for a new team before battling again, or he may step down from the position and call for a new champ.
Thus the unending cycle continues.

There's a lot of other stuff, but the newfags can figure that out on their own. Have fun and be most excellent to each other!

We already have a champ at the moment, current game is:

http://play.pokemonshowdown.com/battle-ou-50587159