Pokémon Brilliant Diamond and Shining Pearl have been updated to version 1.2.0 today by Nintendo. You can get the complete patch notes here.
This patch improved the functionality of the Union rooms They have been expanded to increase the maximum number of players. Other features that have been added include the Colosseum battle. Pokémon Trading and Battles has been modified to apply to some of the illicit Pokémon so they cannot be traded.