Version 1.2.0 for Pokémon Brilliant Diamond and Shining Pearl has been released and is available for download now. This latest update includes expanding the Union Room functionality and adding Colosseum battles.
The maximum number of players in a Union Room has been expanded; now, up to eight players can join a room via local or internet communication. Players can show others their Trainer Cards or Capsule Decorations in the room by selecting the Greeting or Capsule Decorations options.
As part of this latest update, the 2nd floor of every Pokémon Center will now have the option to enter or create a Colosseum Battle. Players can set their own rules in the Colosseum. The rules include the number of Pokémon to be sent into battle, what levels the Pokémon can be, and whether the battles will either be Single Battles, Double Battles, or Multi Battles. Players can enter/make a Colosseum Battle locally or via internet communication.
Version 1.2.0 will also have Pokémon that were obtained “via unintended methods or illicit modification” not be able to be used in Link Trades or Link Battles. Assumingly what the update means is that Pokémon acquired through hacking or other illegal means can no longer be used in trading or online battles. Some “issues” will also be fixed as part of Version 1.2.0.