Question

Like, Sleep Clause. I hear them a lot, but haven't go a clue on what they mean.

Comments

You mean these? They're from Smogon

Clauses

The following clauses must be enabled for all Smogon Tour matches.

Timed Battle
    Select this clause when challenging for all Smogon Tour matches. This is necessary in the interest of finishing the tournament in a speedy manner.
Species Clause
    A player cannot have two of the same Pokémon on their team. For example, a player cannot have two Koffings on his or her team.
Sleep Clause
    A player cannot put two or more different opposing Pokémon to sleep using attacks that induce sleep to opposing Pokémon.
Evasion Clause
    A player cannot increase their Pokémon's evasion stat with a move that specifically increases evasion. Items or indirect boosts do not break this clause.
OHKO Clause
    Players cannot use moves that have a chance of instantly KO opposing Pokémon. For example, Horn Drill is an illegal move to have on a Pokémon's move set.

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you just copied and pasted that.

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Yes I did that is why i said "They're from Smogon", I didn't put it as an answer because I'm not sure if it was right. But if i put it as an answer I might as well include the source.

Answer 1

"A Clause is a restriction placed on the options battlers have other than a simple Pokémon ban. They may prevent certain teams from entering the battle or outlaw choices in battle depending on the situation" (taken from the link below).The clauses applied change with what tier you are battling in, and different tournaments. All the clauses are listed here: http://wiki.pokemon-online.eu/view/Clause