The ultimate villain of the canon series has arrived and he is definitely a threat to the whole multiverse just by existing and having all the six Infinity Stones in his possession. However, considering that Ultron has lorded over a certain alternative reality, how did he get all six? It took the Avengers a lot to get those so how come an evil AI got all in What If..?
How Did Ultron Get All the Infinity Stones in Marvel's What If..? Episode 8
In Marvel's What If..? Episode 8, What If.. Ultron Won?, a cliffhanger ending got some continuity as Ultron, as introduced in Episode 7, got all the infinity stones and wreaked havoc into the universe, and later on, the multiverse, laying waste to life in existence and bringing the peace that he always wanted through eliminating life.
Through the six stones, he was able to get some consciousness of the cosmic beings, one of which is Uatu, The Watcher, who is telling his narrative on how Ultron was able to sit in silence after a winless victory of achieving his true purpose of bringing peace whilst having no one to share it with. Upon realizing the presence of Uatu, he also got aware of the existence of the multiverse.
Uatu holds on to one last hope, pertaining to Nat and Clint who were in the KGB archives looking for what could possibly bring Ultron down and Uatu watched them from afar. They looked for something to fight Ultron with. It would be a plan to combat code versus code as Zola is an analog and Ultron is digital. They went to Siberia, an old HYDRA base, where the last copy of the code of Zola exists.
Ultron wouldn't be so much of a threat with only one Infinity stone as other beings could easily take him down with such. Captain Marvel could have succeeded given how powerful she is. Had Wanda been there, she could easily break Ultron to pieces. However, he got all six of the stones.
Just as Ultron dissipated all life on Earth, Thanos arrived with all the five stones on his gauntlet, and with a flick of the Mind Stone, Ultron cut the Mad Titan in half, easily killing him. All the stones fell to the ground and Ultron realized that such a source of power is so great, he could destroy other planets and galaxies. Thanos was no match at all to him.
All episodes of Marvel's What If..? Season 1 are available to stream on Disney+.