Metagame is basically all of the components to competetive play.
Metagaming is a broad term usually used to define any strategy, action or method used in a game which transcends a prescribed ruleset, uses external factors to affect the game, or goes beyond the supposed limits or environment set by the game. Another definition refers to the game universe outside of the game itself.
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Just take the above and apply it to Pokemon, it is the competetive gaming environment.
