Anything and anyone can be a munchkin (powergamer) in any RPG.
You can be a munchkin in SR, D&D, Conan, Star Wars, AFMBE, Dark Heresy, CoC... I won't name them all. But you can be a powergamer in any single thing you put your mind to, especially RPGs. The question is ; how much of a munchkin do you want to be? Do you -want- to be basically invincible and take down anything that comes your path? Or do you want the gritty, desperate low-power character?
Sometimes I want to play Superman difficulty, where the world is made of cardboard. Sometimes, I feel like playing Charlie Brown, and -I- am the cardboard.
As long as everyone (including GM) know what they are getting into, it's fine. Sometimes, you get to be the Avengers. Sometimes, you're lucky if you wind up looking like the Tick and his merry bunch of sickos.
And as for Deadpool? Too much cyberware, burned some Edge to survive nasty death, ends up looking like chopped liver. Simple, easy, effective.