The Mystery Gift feature must be unlocked by progressing to Jubilife City and speaking to the TV producer on the third floor. This occurs after about two hours of gameplay, though individual gameplay time may vary. Once you have received a gift, it will appear in your bag, party, or Pokémon Storage System.

Where is my mystery Gift?

The Mystery Gift feature becomes available when you speak to your mom after battling the mysterious Pokémon in Slumbering Weald. Once you have received a gift, it will appear in your bag or party. You can select Check Mystery Gifts from the Mystery Gift menu to view the Mystery Gifts you've previously received.

How do I check my mystery Gift in Pokemon brilliant diamond?

Once you've reached that point in Brilliant Diamond and Shining Pearl's story and had the conversation with the TV producer, you can access Mystery Gift from the “X menu” by pressing the “X” button on your Switch.