Will they ever be as powerful as they were in the first movie? In the first Iron Man, the Mark 3 gets shot out of the air by a tank's missile, impacts the ground, and takes little to no structural damage. It then proceeds to blow up the tank and then destroy all of Tony Stark's stolen weapons from afar. In the same movie his suit's flight was able to break the sound barrier.

Fast forward to Iron Man 3, when he is fighting solely with prototype suits for the majority of the film, and they are generally weak enough to break apart upon getting hit by a truck. Still, even his Mark 6 suit, which went toe to toe with Thor in the Avengers, gets easily sliced in half by Aldrich Killian.

Then in Captain America: Civil War, the Mark 43, which is his latest model and the one he used to destroy Ultron's first body, is now weak enough to be fazed by Captain America's punches. How exactly did we get from brushing off tank artillery to being manhandled by someone who, by all rights, should not be able to hit as hard as a tank?

In reality I know the reason for this: Captain America had to win that fight, somehow. It was his movie, after all. When they made the first Iron Man movie, Marvel Studios likely didn't know how far they would get with the Avengers franchise, or have any idea that one day they'd be pitting Iron Man against Captain America. So it makes sense that the power of the Iron Man suit is inconsistent, since it's however strong each movie needs it to be.

The question is: will the suits ever be as powerful as the classic Mark III again? With Infinity Wars coming up, I can see it happening. Captain America has been getting stronger every movie in order to be able to take on new threats. So it's not farfetched to think that with Thanos rearing his head, Iron Man may go back to brushing off tank missiles, or the alien variation of them at the very least. Thoughts?

His suits are technically as powerful as they ever were and yet you are still correct. For the first point about Iron Man 3 the concept Conservation of Ninjutsu is applied whether intentionally or not. If you haven't seen the term/trope before just give it a quick google to shed some light. Happens everywhere. The greater the number of any force, the lower the stats and competence of each unit.

They wanted to:

• Show a lot of Iron Man suits in battle
• Show the power of the extremis warriors

It stands to reason that this would happen. If I was to be apologetic for it and reach into the ether for excuses, I would infer that the large bulk of those suits were for some industrial use and not all were made for war like the Mark 3 (which is actually true). That and there is also the trade-off that may have come from modularity. The original suit was bolstered on and assembled by industrial strength equipment. It was a strong power suit built like a tank to tank shots from tanks but deployment was big no-no. The newer suits are all built for remote deployment and assembly and perhaps there is an inherent structural weakness trade for adaptability.

With the fight against Captain America I can only invoke the excuse of points of failure, It's not like Cap actually shredded Tony's whole armour apart. The tank shell hit Tony in the mid-section of his armour which is solidly reinforced with plates of metal. Cap aimed from specific spots to reduce functionality. Aside from that knocking him around a bit was the best he could do and I don't think he really damaged the armour much until the last portion of the fight with shield aimed at a point of failure(chest and head units). Add to that the fact that this is an opponent that Tony wasn't using his entire arsenal against. Normally he's hitting back with mini-missiles, lasers and repulsor dialed up to eleven; not his fists. So he's never really given many opponents the opportunity to tear into him at melee range for free or hit specific points of failure on his armour.

Iron Man is not really weakening. As you have pointed out, the speed and in-air superiority with which the Mark 43 took down Ultron shows that when he's intent on actually breaking something he'll break it with weaponry and preferably from a distance. High temperature blades and melee range superhumans are clearly just not his cup of tea.