There's a couple I'd like to be able to do.
From Street Fighter -
Wish I could just grab someone and pile drive them into the ground Zangieff style.
Dhalsims stretching arms so I could reach out across a room and punch someone in the face.
From Mortal Kombat -
Be able to freeze people at will like Sub-Zero
Be able to throw that hook and grab people from 50 feet away like Scorpion and say in a really cool voice "Get over here"
