Mystery Gift
How to get mystery gift was actually written in a little booklet that came with the game, but just in case, here's how to get mystery gift.First, fly or bike or whatever to Jubilife city. Enter the Jubilife TV building and go to the third floor. There you'll meet the TV producer. He'll ask you to tell him your opinion on TV. Make sure you say YES. Next, Enter the opinion on TV as EVERYONE HAPPY, and enter the feedback on TV as WI-FI CONNECTION. Once your done, save your game and turn off your DS. When you go back into your game, The MYSTERY GIFT option should be there. If not, leave the building and follow the steps again.
Now that you have mystery gift, you might not even know what it is! Mystery gift is an option that will let you receive gifts from different Nintendo events, or to receive gifts from games like Pokemon Battle Revolution(for Wii). For example, you get a gift Pikachu from the game Pokemon battle revolution after you complete the game. To get the Pokemon, you'll need Mystery Gift in your DS game to connect to the Wii and receive your gift.