Wow, this was pretty good. I think you should do more of these :)
Do you hope Mewtwo will be DLC for Smash 4? I want that.

Only thing that bugged me was that Bowser was a little out of character, other than that this story was actually very impressive. Good job.

What a good one-shot. Not really a romance, but good nonetheless. If only it were longer with Lucario and Bowser going to Mewtwo's fortress. But hey, that adds to the 'reader chooses what they think' type of writing. Good job with this.