The combination of the vibranium and the cosmic energy from the Mind Stone embedded in his forehead not only gave him life and immense intelligence, but also granted Ultron an extremely large number of superhuman capabilities.
Upon locating the Watcher, Ultron fights him across multiple realities and emerges victorious, but the former flees before he can be killed. Ultron assumes control of the Watcher's observatory, now having countless universes to attack.
Without the Infinity Stones, Thanos is physically stronger than Ultron. However, Ultron is more ruthless and has the ability to transfer his mind to any of his other bodies. Ultron might not want to damage his Vision husk, but he can have the universe at his feet whenever he wants now.
Why Ultron was able to use the Infinity Stones in What If?
#WhatIf's #Ultron was able to utilize the Infinity Stones outside of his own universe since he was "power[ing] himself" as a "same universe being," according to the series' head writer!
Why INFINITY ULTRON Is So Much Better With the Infinity Stones Than Anyone Else
Is What If Ultron stronger than Thanos?
In Marvel's What If…?, Ultron used the Mind Stone to instantly bisect Thanos before the two could properly fight. In a fight without any Infinity Stones, however, Thanos would destroy Ultron, further cementing him as one of the MCU's deadliest threats.
After the fall of HYDRA, the Scepter was recovered by the Avengers. It was taken by Ultron and its blue gem casing was shattered, releasing the stone inside it and placing it on the being that would become Vision.
If neither had any Infinity Stones available, Thanos would most likely win a fight against Ultron fairly easily, but since Ultron was "born" using the Mind Stone, there would have been no instance where the two could have met in the standard MCU where Ultron didn't possess it.
The technology of Ultron is so powerful that two of the most dangerous Avengers can get insta-killed casually without either seeing it coming. Ultron defeated both She-Hulk and the Hulk not by outsmarting them or even besting them in a real one-on-one fight, but by overwhelming them both with his strength.
Why Kang would beat Thanos. Kang isn't physically stronger than Thanos, and if the two were to square up in a one-vs-one fight then the Titan would arguably win. However, Kang's knowledge of the multiverse means that would quite literally be several steps ahead of Thanos at all times. As a result, Kang wins this battle ...
Molecular Rearranger - This device allows Ultron to make its adamantium components temporarily more malleable so that it can alter its body structure. While it is an impressively powerful tool, it is also Ultron's greatest weakness.
But if you want to know why he came so close, it's because he is a far more advanced AI than Jarvis. Jarvis was created just from Tony's genius, nothing more. Ultron was created using the sentience of an Infinity Stone, the Mind Stone. His AI is faster-learning and arguably smarter than any human mind.
This is a huge and humiliating end for the Asgardian trickster, and proves that as powerful as Loki is, even he cannot resist the technological terror of Ultron.
Ultron sees the Avengers as one of the main problems with the world's stunted evolution. He particularly dislikes his maker Tony Stark and flies into a rage when compared to him. The evil A.I. has a particular dislike for Vision who inhabits the powerful body Ultron had built for himself.
Rather than the outcome viewers saw in the main MCU, here Thanos died after being split in half by a single blast from Ultron Vision's Mind Stone. Outside of Marvel's What If…? episode 8, the show's interpretation of Thanos has been met with some degree of criticism.
Tony said he saw "a suit of armor around the world," and that he needed Ultron to run the Iron Legion. But JARVIS was already doing a pretty decent job of that, and he didn't seem to have reached the height of his capabilities.
Of course, he doesn't even have to be like that in order to defeat Ultron's best version. Superman can simply fly into a neutron star while fighting the robot and absorb all the radiation which can turn him into something Ultron simply has no chance of defeating.
Despite his immense power, the Hulk has been defeated by heroes like Wolverine, Iron Man, Puck, and the Punisher. Spider-Man, Fantastic Four, and the Thing have also managed to take down the Hulk using their intelligence, teamwork, and unique abilities.
A machine can pick up the weapon and move it anywhere since it's mindless and incapable of possessing the morals necessary to be considered worthy. By this logic, Ultron himself could have lifted it, but it wouldn't have done him much good.
What Makes Him Pure Evil? He betrayed his creator Pym mere moments after being created, quickly deemed humanity as flawed and has made numerous attempts to wipe out the entire race. He attempted to destroy any of his own creations, such as Vision and Jocasta, when they rebelled against him.
In The Avengers, Loki tried to mind-control both Hawkeye and Iron Man, but while he succeeded with Hawkeye, his attempts failed on Iron Man due to his arc reactor. Iron Man's arc reactor protected him from Loki's scepter, as the scepter needed to touch organic matter to work, and the arc reactor was not skin.
Stark's resistance to the Mind Stone likely stemmed from the new element he created to power his arc reactor in Iron Man 2. Needing the new element to save his life, Tony uses Project Pegasus' resources for help, the same organization which was created to wield the Tesseract's power.
