Characters, both heroic and villainous, will be able to get some sort of combat advantage by making a smartass comment. Basically like a Feint / Bluff thing, but using sarcasm or pop-culture quips to 'stun' a foe and get in an extra-damaging attack. (The character would have 'sneak attack' dice, but only get to use them when they've rendered a person flat-footed through use of humnorous quips.)
Damage done will be *widely* variable. A troll-god's hammer might be able to collapse a building, but it will bounce harmlessly off of a non-superpowered teenagers skull, multiple times, not even leaving a bruise. Instead of damage numbers like '1d8+12' the hammer would do extra dice of damage, say '1d8+3d6,' for instance and PCs will be able to spend action points to minimize damage they are taking (using the extra dice instead of straight damage adds, a PC could reduce that hammer hit to 4 hit points of damage. If they used damage adds, even minimum damage would be 13 hp).
Action points will also allow certain characters to win a combat narratively by blowing action points. When fighting a character that is stronger than the PC, and has proven invulnerable to their attacks, the character will be able to blow some action points, make a determined face (and probably some sort of speech), and utterly kick their ass, with no tactics or plan at all, just using the same attacks they've proven impervious to before. The more precautions the PC takes in such a combat, the less effective they'll be. Aid Other will instead penalize them. They'll do less weapons with magical swords than with their own fists. Tactics or strategems or traps set up before hand will fail spectacularly. Guns will be dropped or jam or prove useless. Highly trained, super-experienced or magically omnipotent allies will bump their heads, screw up and make things worse or suddenly develop a phobia of using their superpowers, proving useless, and the hero must stand alone. Only bullheaded face-punching (after the appropriate speech) will win the day, especially if the villain brags that they've deliberately put the PCs in a situation they can't win.
Any PC or NPC that succeeds at enough 'cool' actions using Action Points or narrative combat will become a core character, while those who have instead played their character intelligently will end up getting sidelined, written out of the game, maimed and / or killed.
Drama is key. A PC that is effective and doesn't screw up a lot and get themselves into all sorts of whacky situations that a brain-damaged hamster could have told them how to avoid is *boring* and will die soon. A bumbler who is funny and always messes up, often resulting in the deaths of teammates will always be welcome at the table, because the terribly incompetent super-people need a terribly incompetent non-super-person to make them feel better about themselves. (Hello, Andrew!)