Player Asymmetry

One of the expectations that can challenged in a team game is of equity. Plenty of conflicts and challenges are approached by people who don't have the same level of resources to offer. But that doesn't mean their contribution is without merit. Look at the American Revolution, where a bunch of under provisioned dissidents took on a global superpower. The drama is still there even if the match-up is "unfair."

Of course for fiction the challenge to the players should be on par with what they are able to accomplish. fighting 50 foot killer robots is not something the normal police can do, leave that to superman. But, a story can involve both Superheroes and those without such powers. Dynamics between players who are mismatched like this can be very interesting. 

Just make sure there is a challenge suited for each level of power. Or try to be creative in ways the little guy can take on Goliath. Such a game might be the most rewarding, if teamwork is made between people of different means.