Pokemon Brilliant Diamond and Shining Pearl players can get a free mythical Pokemon as part of the Pokemon Day celebrations. As announced on the Pokemon Presents stream, you claim a Mystery Gift to get a free Shaymin.
To claim your Shaymin, just start up Brilliant Diamond or Shining Pearl and choose “Get Via Internet” from the Mystery Gift menu. That will grant you an item called Oak’s Letter, which will let you go speak to Professor Oak on Route 224. Assist Professor Oak and the mythical Pokemon Shaymin will appear. Once you’ve added it to your team, you can use a Gracidea item to change it into its Sky Forme.
This is one of a few free updates announced during the Pokemon Presents, which also included a free update for Pokemon Legends Arceus, an upcoming Alola update to Pokemon Go, and more.
The big reveal of the presentation, though, was the announcement of Pokemon Scarlet and Violet, the new Gen 9 games. Those take place in a new so-far unnamed region, with an open structure that does not have barriers between towns and wilderness. The announcement claims you’ll be able to see Pokemon roaming and flying around everywhere, including in towns. We also got a first glimpse at the three starters.
Source: Gamespot