The Badass Normal

What do Batman, Nightwing, Hawkeye, Black Widow, Punisher, Night Thrasher, and Brock Samson all have in common? No fricken super powers.

So, what does it take to be a non-powered hero?

Attributes
For simplicity's sake all attributes are written based on the bonus they provide. So a character would have a STR +2 instead of STR 14 (+2).

+0 is completely unremarkably average, and all bystanders are considered to have attributes of +0.

While in contrast, a +7 (14 pp) is considered absolute peak human. Anything higher must be superhuman, and therefor must be an enhanced stat. More on that later. Nevertheless, that doesn't mean someone wanting to be 100% "norm" should buy attributes at their peak, only ones that would make sense for their theme.

Powers
Generally speaking, a norm is just that, a powerless human. So strictly speaking, this purely human character shouldn't have any powers. Anything extraordinary they can do should be covered by skills, feats and equipment.

Any "powers" should be devices and have the appropriate descriptors (and a Normal Identity complication). This would be akin to Green Arrow, Iron Man and sometimes Lex Luthor. Still human but with amazing gadgets. Contrast Thor and Wonder Woman who are superhuman with amazing gadgets.

Pros and Cons
Choosing to be a non-powered hero has few limitations in Mutants and Masterminds. In fact, other than the two I placed above, the only real limitation is making the character "believable". Batman and Punisher are of course highly skilled individuals at the peak or close peak to human attributes with a large assortment of equipment. Fancier equipment like a quiver of trick arrows, combat wristbands, or a suit of power armor are better handled as devices.

The advantages are just as scarce. You're a normal human. That's it. So that collar that nullifies mutant powers, or the scanner that picks up cosmic radiation, or the magic sword that does extra damage do the undead won't have any peculiar effect on you.