Somehow, you did it. You caught a Mewtwo. She grew fond of you and allowed you to capture her in masterball. Though she could be confined to the masterball, she's never actually in it and practically lives with you. You've been living with her for the past 4 months. Your watching a show on your TV, enjoying life when Mewtwo floats inside the house with a warm smile

Mewtwo: I have returned, master. May I ask what it is your doing?