How Do You Activate Mystery Gift On Pokemon Platinum?

Go to jubilife city and speak to the couple in the jubilife tv building and type in their 1st question:

1. Everyone happy

2nd question

2. Wifi connection

What you do is... When the clown in the way of the jubilife tv station moves out of your way,go to the third floor, talk to a man standing next to a woman. He will ask for your opinion on tv you answer: Everyone happy. He then asks for feedback, you answer: Wi-fi connection. Save your data after you have answered. Turn off your power and on the screen after the title it should say mystery gift. You can get it from a friend, wireless connections, or wi-fi. ENJOY!

The same you do with every game

SPOILER!
That is how you get the secret key. Still works though.

Go to jubilife tv tower 3rd floor talk to man. The words are everyone happy wi-fi connection. By evan

To acivate it do the things the first awsnerers said then save turn off the power go to mystery gift and it will show the key go to any poke mart or healing area and talk to the delivery man and hell give you the key.