Shadow Mewtwo was recently revealed for Pokken Tournament though nobody had any idea when the character would be availble to use. It has now been revealed that Pokken Tournament releases for the Wii U this Spring Shadow Mewtwo will be available as long as you purchase the limited run Shadow Mewtwo Amiibo card. If you don’t get it during the first production run you will have to fulfill certain in game requirements in order to unlock the character for regular gameplay.

If your interested you can see the Amiibo Card below which I think looks pretty cool and will say you should buy even as a simple collectors item:

Shadow Mewtwo Amiibo Card