All you have to do is go to the nearest Wifi spot, turn on your game and do as the following:
1) On menu, choose
Wonder Mail 2) Choose
Receive Wonder Mail 3) Choose
Nintendo Wi-fi Connection 4) Wait for connection, then the
Rescue Mewtwo mission will be on 2nd page.
5) Complete the rescuing mission.
6) Mewtwo will now appear at 6F Dark Crater or 5F Deep Aegis Cave. Make sure you bring Secret Slab or Mystery Part (put in bag for Mewtwo to appear) along with Golden Mask or Amber Tear (leader hold, b/c Mewtwo has low recruit rate).
Please note that the mission is
only available on Wifi (no password) in a limited time so be sure to catch it when you can.
« Last edited by nhahtdh on Oct 8th 2008 »