Dark Void isn't banned in XY Official Metas
Dark Void isn't available in current XY Battle Spot

Smeargle only learns it through Darkrai who isn't available at the moment, but the legality checker does not catch that.
Moves unavailable in XY cannot be sketched.
Merge pull request #486 from V4Victini/patch-11

Moves unavailable in XY cannot be sketched.
Ban Sneasel from Pokebank LC
Merge pull request #487 from MaikeruS/patch-3

Ban Sneasel from Pokebank LC
Merge remote-tracking branch 'upstream/master'