It depends on the specific fanfiction. In some stories, Superior Iron Man might be more powerful because he's willing to push the limits of his technology and his morals further. But in others, Iron Man could be more powerful due to his experience and his ability to work well with others.
Thanos could also win in a fanfiction. He has incredible strength and the power of the Infinity Stones at his disposal. In a lot of fanfictions, the power levels are often exaggerated. Thanos could simply use the Reality Stone to make Iron Man's weapons ineffective or use the Time Stone to freeze Iron Man in time and then defeat him. His brute strength alone is enough to overpower Iron Man in a direct confrontation. And his experience in battles across the universe gives him an advantage over Iron Man who mainly operates on Earth.
In some fanfictions, they might team up against a common enemy that requires both their unique skills. For example, a new super - villain who has the ability to hack into Iron Man's technology and also has super - strength that Spider - Man has to counter with his acrobatic fighting style. They would have to learn to work together, with Iron Man respecting Spider - Man's instincts and Spider - Man learning to trust Iron Man's strategic plans.
In some fanfictions, the winner isn't really about who is more powerful physically or technologically. It could be about who has the stronger will or the better moral compass. For example, if Iron Man realizes that he's in the wrong during the fight, he might back down, making Spider - Man the 'winner' in a sense. Or if Spider - Man is able to convince Iron Man of a greater good, the fight could end without a clear physical victor.
One possible plot could be that Iron Man and Batman initially clash due to their different methods. Iron Man, with his high - tech and flashy approach, might see Batman's more brooding and stealthy style as old - fashioned. But then they realize they are both fighting for justice in their own cities. They could team up to take on a common enemy like a powerful tech - savvy criminal who is causing chaos in both Gotham and New York. Maybe they combine their skills, Iron Man's advanced weaponry and flight capabilities with Batman's detective skills and knowledge of the criminal underworld.
One possible plot could be that Batman and Iron Man meet when a new global threat emerges that requires both their skills and resources. Maybe it's a high - tech villain who is stealing advanced technology from Wayne Enterprises and Stark Industries. They start off distrustful of each other, with Batman being suspicious of Iron Man's more flamboyant and open - ended methods, and Iron Man thinking Batman is too much of a lone wolf. But as they work together, they learn from each other's strengths. Batman teaches Iron Man about stealth and hand - to - hand combat, while Iron Man shows Batman new ways to use technology for crime - fighting.
The differences between them are significant. Lex Luthor is more of a traditional villain in the short story. He is jealous of Superman mainly and wants to prove his superiority through his intelligence and inventions. His technology is sometimes more experimental and untested. Iron Man, however, is a hero who has refined his suit over time. His technology is reliable and battle - tested. In terms of character, Iron Man is more self - sacrificing. He is willing to put himself in danger to protect others. Lex Luthor is more concerned with his own status and power. Their methods of achieving their goals are also different. Iron Man uses his technology to directly combat threats, while Lex Luthor may use more underhanded means like manipulation and subterfuge.
Iron Man would probably win. He has a highly advanced suit with a plethora of weapons and defensive systems. His suit is constantly evolving and he has the genius of Tony Stark behind it. Metallo, while strong with his kryptonite - powered body, Iron Man could analyze his weaknesses and use his repulsors, missiles and other gadgets to take him down.
One interesting plot could be where Metallo somehow gets an upgrade that can disrupt Iron Man's technology. Then Iron Man has to rely on his wits and basic engineering skills to fight back. Another could be a scenario where Iron Man has to protect a city from Metallo without using his full - powered suit, making it a more challenging fight.