On that note, and ahead of next year's release of Avengers 4 on May 3, 2019, we have decided to take a look back and investigate how Tony Stark (Robert Downey Jr.) has changed, evolved, and modified his suits with each passing film ever since he decided to take on the mantle of Iron Man. We have several different movies to get to, so let's get started at the very beginning: 2008's Iron Man.
The one that started it all. Without Jon Favreau's Iron Man, there would be no Tony Stark, and this is the film that offered up the armored Avenger in his crudest and most rudimentary form. As the origin story of the beloved hero, this is the film that gives us the basic idea of what Iron Man is at his core. To accomplish that, the film shows us the Mk. 1 armor during Tony's imprisonment, which is a bulky walking tank that's mostly used for melee combat but also features some rockets and flamethrowers, plus whatever other weapons he could jerry-rig during his time in the cave.
After his escape and his return home to Southern California, Tony gets to work in his garage and puts together a couple of different Iron Man suits. The advancements seen in this movie include him figuring out how to prevent ice buildup at high altitudes, changing the color to the now-iconic red and gold scheme that we know and love, and perfecting the repulsor weaponry.
Iron Man 2
Though Tony Stark did make an appearance in The Incredible Hulk, the next appearance of the Iron Man armor came during the events of Iron Man 2. In this movie, it's all about fine-tuning the weaponry and gadgetry that appeared in the first film. Specifically, Tony's ability to get the armor on and off in a pinch improves considerably, and the inclusion of the modular briefcase suit shows that he's committed to developing more than one version of the armor to suit a particular need -- in this case, portability.
However, the third act of the movie also shows other major improvement to the Iron Man armor design in the evolution of the arc reactor. The main narrative through-line of Iron Man 2 is that the palladium-based reactor in his chest is killing him, so he eventually gets to work and develops a brand-new element to enhance the suit and provide him with a more stable and healthy means of keeping him alive. Though it's not explicitly stated in the movie, this element turns out to be vibranium.