He can do his own stunts. Anyone whose seen the bourne trilogy knows that he can do a deep tortured and intense character very well and is a brilliant character. I could also see him being a billionaire playboy. So I can't think of any reason he should considered. He'd be better than Ryan Gosling or Bradley Cooper.
Plot: Something like Year one and Zero year where we have a recently returned Bruce wayne take up the cowl and become to cape crusader. The main villain and mobster he should go up against should the black mask since he has never been in a batman movie even though he is an awesome villain. The black mask, seeing batman as a threat, hires deathstroke to take him out.
Scenario: fight is at the Queen Mansion in the living room. Oliver and John are 10 feet apart. This is just h2h. Oliver is in his arrow costume but doesn't have his bow or arrow. John doesn't have his gun. Morals on and Oliver knows who John is.
Fight is in metropolis. This is the current Doctor who( Matt Smith) and he has a month and a half prep with access to the tardus. Green Lauterns: Hal Jordan, Sinestro, Guy garner, John stewart, and Kyle rayner. Start from 100 yards away. morals on.
Scenario: Superior has decide to break in the Uncanny xforce. He has a week prep. Fight is at the X force's base. All of the X force has standard equipment. Start from 30 yards away. morals on. X force: Cable, Colossus, Domino, Forge, Doctor Nemesis, and Hope summers
Fight is in Central Park. Connor has his tomahawk, hidden blades, his bow and 45 arrows, and 5 rope darts, Clint has 1 katanas, 2 sais, his bow and 45 arrows, and 10 throwing stars. Start from 30 yards away. morals on