Things You'll Need
Instructions
Start a new game or continue your saved game. Progress through the game to the fourth mission and save your game.
Reset the DS and return to the game's title screen. A new option called "Ranger Net" will be available. Choose "Ranger Net" by selecting it and pressing the "A" button.
Select "Download Special Mission."
Go to the mission titled "Deoxys and the Mysterious Temple" and download it onto your DS.
Have at least one friend complete steps 1 through 4. These missions can have up to four people playing at once.
Choose "Play Special Mission" and then pick the "Deoxys and the Mysterious Temple" mission. Both players must do this. Make sure you and your friend choose the multiplayer mission.
Allow the two DS systems to connect. This will happen automatically, as long as they are both within range of each other. The systems should be no more than three feet apart during the connection. Once the connection has been made, the mission will start.
Flip the two switches that block your path. You have to do this simultaneously with your friend. This happens at the beginning of the level and allows you to enter the temple itself.
Make your way through the temple by capturing or avoiding the various Pokemon that block your path.
Run into Deoxys at the end of the temple to start a battle.
Draw circles around Deoxys while releasing your Pokemon on him. Your Pokemon will attack Deoxys and lower his health. Eventually, Deoxys will give up and join your party.