Maybe she asked you to do something but you didn't listen because you were too busy playing, so she got pissed and turned the power off. We didn't hear your step-mom's side yet.
That was just a figure of speech, she was just trying to say that in order to fight someone who owns a Thanatos card, one must switch armors/equips,etc back and forth in order to confuse that certain person.
I think that would also lead to world destruction, because what if Mewtwo was summoned?, he'll be unstoppable. Even if we tried to end his domination, we're going to fail, because he's to great and far more superior than us and any other pokemon out there.
Sniper is an easy kill when it's still in early/starting game, why? first, he doesn't have any escaping skills like windwalks and such, second, he has a low hp. You just need to prevent him from farming by harassing him in early game.