Wonder Trades were introduced to the Pokémon series in X and Y, and allowed players to just randomly trade their Pokémon with other players that were using the feature. It quickly became something that fans appreciated, and folks out there are wondering if you can do Wonder Trades in Pokémon Brilliant Diamond and Shining Pearl.
At the moment, the answer is no, you cannot do Wonder Trades in Pokémon Brilliant Diamond and Shining Pearl, but that does not mean that you will not be able to do them forever. The overall design of the games has fundamentally changed since X and Y, and one note from the recent article by Nintendo on their upcoming patches does hint at some potential.
A future update will introduce a Global Wonder Station Link Trade system at the facility in Jubilife City. So, while it is hardly set in stone, there is some potential there for Wonder Trades in the future. If it were to return, it would make getting Pokémon from all around the world very easy, which would be excellent for breeding Pokemon and hunting Shiny versions.