Captain America And Star-Lord
Why It Would Be Great: Could you imagine Captain America’s inherent patriotism paired with Star-Lord’s more selfish tendencies?
Putting these two together would force them to learn a lot about how the other side lives. Star-Lord would learn what it’s like to truly be a selfless hero, while Captain America would be forced to acknowledge that sometimes you need to do a bit of bad to do good. It would be an interesting battle of wills as Star-Lord would constantly try to assert his dominance and presence in a way that mimics Captain America, but would probably keep failing.
The Best Part: Captain America’s delight at finding out he’s more up-to-date on pop culture than someone!
Black Widow And Ant-Man
Why It Would Be Great: Although their personalities wildly differ, it wouldn’t be too hard to imagine Black Widow and Ant-Man teaming up for a similar goal.
After all, Black Widow is a spy and Ant-Man is a thief, so a plot revolving around stealing classified information wouldn’t be outside the (quantum) realm of possibility. But now imagine Marvel’s most level-headed superspy paired with one of its most bumbling heroes. Forcing Ant-Man to be a spy would be in line with his character abilities, but he would be totally out of his depth working with the efficient and dedicated Black Widow.
The Best Part: Black Widow trying to teach Ant-Man how to stay cool under pressure, with hilariously disastrous results.