When a threat descends on Earth in the MCU, they call in the Avengers. When a threat pops up in space in the MCU, they call in the Guardians of the Galaxy. And when the Multiverse itself is under threat, it's time to call in the big guns that go by the name the Guardians of the Multiverse.
The first season of What If...? laid the groundwork for this team, leading up to its somewhat official formation. It's an interesting group, to say the least, and is one whose members have varying degrees of intelligence. And it's no surprise who tops the list.
7 Thor Isn't Particularly Bright In Any Universe
The iteration of Thor introduced in What If...? is colloquially known as Party Thor. And the reason for that is extremely simple as the guy just loves to party, to the point that it can actually be to the detriment to all of the realms. No one would accuse Party Thor of being particularly smart. But the key thing about this scenario is the fact that he isn't exactly the smartest guy in any reality.
To be blunt, the Sacred Timeline version of Thor who fans know and love isn't all that intelligent. That's why Loki was able to play his adoptive brother like a fiddle for so many millennia. It's best to just let the man do what he's good at and that usually involves bringing the thunder.
6 This Version Of Gamora Is Even More Dangerous
Calling Gamora the most dangerous woman in the galaxy is an understatement, to say the least. Thanos adopted her at a young age and raised her to be an expert in numerous forms of both armed and unarmed combat. And that's the nice version of her from the Sacred Timeline.
The Guardians of the Multiverse version of Gamora is somehow even more dangerous. She was successful in killing her father, then started wearing his trademarked armor and carried his sword. This is someone who has earned the fear and recognition that comes with her skills. No one would ever suggest Gamora is stupid, mainly because she would kill that person, but she still has the same normal level of intelligence as always.
5 Killmonger Is Both Cagey And Vicious
The Guardians of the Multiverse version of Erik Killmonger led a similar life to his Sacred Timeline counterpart. His uncle T'Chaka killed his father, leaving a very young Erik to fend for himself in America. He grew up to become the reigning champion of spec ops killing machines in the MCU.
But saving Tony Stark before the Ten Rings could attack and kidnap him sent What If...? Killmonger in a new direction. He was able to kill James Rhodes, Tony Stark, Klaue, and T'Challa, taking everything he wanted for himself. He played every angle provided to him perfectly, proving once again that he is easily one of the savviest individuals in the entire MCU.
4 Captain Carter Is Master Of Strategy
When the experiment that turned Steve Rogers into Captain America was disrupted, the MCU was graced with the arrival of Captain Carter. This iteration of Peggy Carter took the Super Soldier Serum and became the defining warrior of World War II. With a shield in one hand and a sword in the other, she took on the beast that Red Skull tried to release and won the day.
Naturally, Uatu the Watcher called her in to be part of his Guardians of the Multiverse. Few people are as brilliant a strategist as Peggy Carter or have the innate combat sense she does. She has always been one of the smartest people in the game, particularly on the battlefield.
3 The Genius Of Doctor Strange Always Shines Through
Long before Stephen Strange started his training to become a sorcerer, he was an absolutely brilliant doctor. He spent years of his life studying to become possibly the greatest neurosurgeon in the world. But a car accident destroyed his hands, taking that away from him and sending Strange on the path that led him to carry the mantle of Sorcerer Supreme. In What If...?, things took a much darker turn.
In that reality, the same accident also killed his girlfriend, Christine. His attempts to change the past and save her resulted in the complete destruction of his reality, leaving him as the only survivor. Strange may have made a truly horrifying choice but that doesn't change his level of intelligence.
2 Black Widow Outlasted Ultron
It's borderline impossible to deny how smart Black Widow is. Her Red Room training combined with untold years in the service of S.H.I.E.L.D. turned her into the world's greatest spy. But there is a lot more to her than that.
Black Widow is far more intelligent than anyone seems to give her credit for. If she didn't have the brains to back up her skills, she never would have survived as long as she did. That goes double for the version of Black Widow who joined the Guardians of the Multiverse. She managed to outwit Ultron and survive when he killed literally everyone else. That definitely counts for something.
1 This Star-Lord Is A Super-Smart Space T'Challa
When it comes to being a superhero, few have the resources of T'Challa. He is a highly-trained hand-to-hand fighter who has superhuman skills thanks to ingesting the heart-shaped herb. He has the backing of an ultra-wealthy, technologically advanced nation that has access to the world's only source of Vibranium. And he's also incredibly smart, almost on the level of Tony Stark.
What If...?'s version of T'Challa is even smarter after spending decades in space, learning about things most humans couldn't even dream of. This combination of exotic knowledge and experience has only served to make this version of the character even more intelligent.