From Bulbanews, your community Pokémon newspaper.
Dark Void to be banned
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Dark Void will no longer be allowed
The rules for Wi-Fi battles are set to change in Pokémon Black and White on Dec. 27. While the main changes reinforce the restrictions on hacked Pokémon, the move Dark Void will also be banned from use.
The article states that Pokémon are only allowed to use moves learned by leveling up, through a TM or HM, breeding, in-game events, or out of game events. The only exceptions to this are the moves Sky Drop, which was previously banned, and Dark Void, which will be banned when the rule change goes into effect. The only Pokémon that can learn Dark Void are Darkrai, who is already on the list of banned Pokémon, and Smeargle, who can Sketch the move from Darkrai.
The second half of the article talks about how any player with hacked Pokémon will not be allowed to compete in Wi-Fi battling, and that in any future official Pokémon tournaments, these rules will be added.