Random Matchup Ruleset

[Jibaku*]

A few of you may be unaware what the game's rules are. For reference, here they are (taken mostly from Sprocket's original thread, with a few edits)

Random Matchup Rules

• Number of Pokemon: You can bring up to 6 Pokemon with you. For the battle, however, you will pick 3 for Singles, 4 for Doubles and Rotation, and 6 for Triples, and the remaining Pokemon will not be used. You must always bring the minimum number of Pokemon.
• Team Preview: Team Preview is always on. You see your opponent's team before you pick your Pokemon.
• Pokemon Level: All Pokemon above level 50 become level 50 for the duration of the fight. Pokemon below level 50 do not have their level adjusted.
• "Special Pokemon" Clause: Special Pokemon are banned. Full list is below.
• Species Clause: No two Pokemon on your team may have the same Species number
• Item Clause: No two Pokemon on your team may have the same Item equipped
• Wonder Launcher: Wonder Launcher use is optional.
• Sky Drop Clause: No Pokemon may use the move Sky Drop.
• Soul Dew Clause: No Pokemon can hold a Soul Dew

UPDATE: Dark Void will be banned from the GBU from December 27th, 2011 onwards

Number of Pokemon & Team Preview

Depending on the format, you must bring a minimum number of Pokemon with you into the battle room. From that list, you will see all of the Pokemon your opponent brought, and you will pick the appropriate number of Pokemon from your list. You can also decide the order that your Pokemon will be arranged in your Party.

For Singles battles, you must bring 3 to 6 Pokemon, and you will pick 3 of those Pokemon to battle.

For Doubles battles, you must bring 4 to 6 Pokemon, and you will pick 4 of those Pokemon to battle.

For Triples battles, you must bring 6 Pokemon. You will decide the order that all six Pokemon are called out in.

For Rotation battles, you must bring 4 to 6 Pokemon, and you will pick 4 of those Pokemon to battle.

Team Preview is always on, and cannot be turned off.

If this doesn't make sense, lets consider this singles battle example of Ash Ketchum and Gary Oak.

Ash Ketchum brings into the battle room the following Pokemon: Pikachu, Venusaur, Charizard, Blastoise, Snorlax, Lapras

Gary Oak brings into the battle room the following Pokemon: Exeggutor, Arcanine, Machamp, Tyranitar, Pidgeot, Rhyperior

Due to Team Preview, both sides get to see each others' teams before they pick their three Pokemon.

Having looked at the opposing team, Ash decides to bring out Venusaur, Charizard, and Blastoise. Likewise, Gary decides to bring out Exeggutor, Arcanine, and Machamp. The remaining Pokemon (Pikachu, Snorlax, Lapras, Tyranitar, Pidgeot, and Rhyperior) do not get used at all.


Pokemon Level

All Pokemon fight at level 50 or below. Pokemon that are level 51 or higher are reduced to level 50 for the duration of the fight. Pokemon that are level 49 and below do not have their level changed. Any moves that your Pokemon know will not be forgotten, even if they cannot legally learn them at level 50.

For example, if I bring a level 100 Azelf, it will become level 50 for the battle.

However, if I bring a level 1 Aron, it will remain at Level 1 for the battle.


Special Clause
(AKA the Ban List)

Special Pokemon are banned. Essentially this is all Version Mascot Legendaries, other ultra-powerful legendaries, event-only Pokemon, and Chatot. The full list is:

#150 Mewtwo
#151 Mew
#249 Lugia
#250 Ho-Oh
#251 Celebi
#382 Kyogre
#383 Groudon
#384 Rayquaza
#385 Jirachi
#386 Deoxys
#441 Chatot (lol)
#483 Dialga
#484 Palkia
#487 Giratina
#489 Phione
#490 Manaphy
#491 Darkrai
#492 Shaymin
#493 Arceus
#494 Victini
#643 Reshiram
#644 Zekrom
#646 Kyurem
#647 Keldeo
#648 Meloetta
#649 Genesect

Species Clause

No two Pokemon on the same team may have the same Species number.

For example, you can only carry a single Rotom on your team, since all Rotom forms have the same Species number.

Item Clause

No two Pokemon on the same team may hold the same Item at the start of battle. However, the utilization of Trick to obtain two or more of the same items during battle is allowed.

Other

Since this is an official Nintendo Meta-Game, other rules that Smogon battlers follow in Standard OU don't apply:

Sleep Clause is off (Any number of Pokemon can be put to sleep)
OHKO Clause is off (OHKO moves like Fissure are legal)
Evasion Clause is off (Double Team and Minimize are legal)
There is no Ability ban list (Drizzle + Swift Swim, Moody, etc, are legal)

[Jibaku*]

Updated with Dark Void ban