Weapons: Lieutenant James Rhodes uses his somewhat-legally acquired Iron Man suit. It has various lasers, missiles, projectiles and guns, the most prominent of which is the machine gun/repeating cannon on his shoulder. Bucky Barnes also carries a remarkable amount of guns on various body-parts, as well as grenades, knives and the sniper rifle. And that brings us to the arm. Yeah, that arm. The one that withstood a repulsor blast a point blank range, held it’s ground against Cap’s shield and has beaten the crap out of a lot of unfortunate people over the years. It’s a cybernetic prosthetic with increased strength and reaction speed, near indestructibility and an electric shock feature. As cool as that sounds, War Machine has more firepower, and is better in this category.
Defenses/weakness: The Iron Patriot has a suit that’s *almost* as good as Tony Stark’s. It protects him from virtually anything anyone can throw at him, and saved his life in a thousand-foot free-fall. His weakness is his suit’s heart. Bucky can use his arm as a shield, but it really doesn’t compare. His weakness is his Winter Soldier activation code. War Machine wins again.
Skill: Iron Man’s renegade sidekick is not kidding around with the suit. He has effortless control over it that translates to deadly accuracy on the battlefield. His weakness is that he isn’t good at hand-to-hand combat. Bucky has the cold precision of a Nazi super-soldier. Combined with Russian sniper accuracy and martial arts skill that rival Bruce Lee, he is a force to be reckoned with. The Winter Soldier wins here.
Mindset/intentions: War Machine is a dedicated patriot, and does everything for his country. The Winter Soldier has been a spy, assassin, sniper, commando, and has done every other unsavory job the Nazis had to offer. Even now that he is free of the mind-control, that mindset stuck, and there is nothing Rhodes can do about it. Rhodes has no intention of taking Barnes alive, as he was a Nazi spy. After seeing Bucky fight, I doubt he intends to spare Rhodes. This is a tie, because it’s basically the same mindset with different motives.
Use of Surroundings: War Machine usually stays focused on his armor, and gives little thought to his surroundings. The Winter Soldier on the other hand not only uses the location as a tool, but manipulates it to fit his style.
If we give back Bucky his left arm and Rhodes the use of his legs, or have this battle before the events of Civil War, this is not an easy win for either. War Machine has more firepower, but lacks the close quarters skills. Bucky could evade and block his fire for a while, and would probably make some sort of leap-of-faith onto War Machine’s back, where he wouldn’t be able shoot him. He would probably go for the guns, so he is forced to land and face him hand to hand. This would not slow War Machine down, but Barnes might be able to throw him on the ground long enough to rip off the mask part of the suit, giving him a target to shoot for. War Machine would fly away, then fly straight at Bucky. Bucky wouldn’t miss–he never misses–and he would kill War Machine.
But whether Bucky survives or not is a completely different problem. His main guns may be damaged, but Rhodes still has plenty firepower, not to mention force of impact. Unless Cap shows up to save the day, this fight may be a double-death, and the last we see of the Winter Soldier.