One of the funniest tropes to me in comic books and by extension, movies, is this annoying need to prove how equal most heroes are, despite all evidence to the contrary. The "Goku v. Superman" debate made endless, except turned even more pointless by making it less "Goku v. Superman" and having it be "Krillin v. Superman" or "Hawkeye v. Goku".
Civil War seemed especially egregious of this based on the trailers. While I haven't seen the movie yet, I will go off the trailer and what the other movies have established.
Team Iron Man consists of no less than three nigh indestructible robots/robot-armored heroes with the capacity for flight and a combined arsenal to rival most battleships. And one of these heroes is so pure and noble, that he alone is the only other hero worthy of wielding Mjolnir. Another is equipped with claws that can actually rend through Cap's vibranium shield. And another has superhuman reflexes, strength, and agility beyond even Captain and Bucky with the ability to bind and contain people. Three of these heroes are supposed to have a genius intellect, and a fourth is a goddamn super computer made "flesh". Oh, and a master assassin to round it all out.
Meanwhile, on Cap's side, we have two guys who are strong and fast. Not as strong and fast as Spiderman, but still. Then there's bow and arrow guy and hang glider man, who'll surely come in handy against the flying juggernauts. The only two with legitimate powers, a guy who can shrink and increase his strength and a woman with non-descript magic powers, are stuck on the ground, unless ants can now survive flamethrowers and lasers and propulsion blasts. And even Cap's strongest ally, Scarlet Witch, got her ass kicked by freaking Hawkeye of all people. Not to mention, Captain's side is almost exclusively ex-criminals and the less than brilliant of the Marvel world.
Even if they were genius, what hope do they have? To recap, the defensive capabilities of Iron Man's side include 3 people with almost invulnerable armor, a suit made out of Captain America's shield materials, and one of the most agile heroes in the Marvelverse. Their offensive capabilities include lasers, cannons, rockets, daggers, claws, webbing, and good ole fashioned metal fists. To counter all that, Captain America's side has, ahem, a shield that only covers part of one person's torso (seriously more people should just shoot his legs) and Winter Soldier's metal arm. Their offense includes bullets, gloved fists, and *gasp* arrows, none of which are dangerous to the 4 heroes sporting serious armor. Scarlet Witch is doing some seriously heavy lifting on this team based on whatever the hell the writer's decide her powers will be for this movie.
TL;DR: Unless Hawkeye's got another USB arrow he can shoot up Iron Man's ass, it'll probably be the funniest thing in the movie to see how they justify how Team America even has a chance against Team Stark.