While it was missing in A1, I think in A2 we will see that Hawkeye can do sassy as well as the kind of "My Life Is A Weapon" humor that simply comes from him getting in certain situations, and I think these styles of humor could act as a really good match with T'Challa. If you put anyone to slapstick next to T'Challa I think the effect would be too cartoonish despite it working in GotG. I think the aim should be closer to C:TWA which features a more serious leader type with the weight of the world on his shoulders balanced out by a deadpan snaker in Black Widow.
I like a Clint who can deadpan a line but then gets this smug smile on his face and looks back to his partner to make sure someone's appreciated the joke. So someone between Tony's humor as a crutch and cry for attention and Natasha's poker-faced one liners. Clint can play the cool, well trained agent with the SHIELD issued snark while also being a bit of a show off; he doesn't quip because it's his natural response to high stress situations or even because he's just a born deadpan snarker. He does it because on some level he wants people to hear him being witty. That's a show off style attribute that could work for the character.
On the other hand, T'Challa's humor should come from his natural fast wit and powers of observation. If you know anyone who is freakishly smart and incredible perspective you know they can be wickedly funny, and it all comes from being able to quickly recognize the inherent humor in a situation and bringing attention to it with a natural ease.
The biggest problem is I think this humor tends to work better once T'Challa is outside Wakanda or a least interacting with non-Wakandians. It's kind of a Fish-Out-Of-Water scenario, only in this case the fish is pointing out how strange it is that both our species require water and air to survive but while he simply lives in oxidized water, we've put hundred of miles between us and the cost line and simply hope it fall from the sky and build all sorts of pipes to bring it to us. A lot can come from an outsider recognizing the oddness and deconstructing our customs and culture. These observations highlight a character's intelligence while also being funny, so it's a good match for T'Challa.
I think adding Hawkeye does more than just gives you a funnyman, though, with his position being a more typically fish out of water tale. I think it connects Black Panther very immediately back to the Avengers in a way that, written properly, wouldn't feel forced or overshadow Black Panther. I do wonder if, since he is a lesser well known property in the GA eyes and because he is he first true global Avenger that some people might not feel as immediately drawn in the way the were for others. Let's face it even in the comics Black Panther holds a rather unique position since, a the ruller of an African Nation and a member of a team sworn to protect the world. Adding in Hawkeye shows that, yes, this character is an Avenger even if he's not in America. Which may be stupid obvious to all of us, but isn't this the sort of things studios worry about?
Plus, Hawkeye (while awesome) isn't going to outshine Black Panther. He'll not only have his suit and herbs, but also a home feild and scientific knowledge advantage. He's definitely set to be the leader in this mission. At the same time, Hawkeye offers some tonally appropriate humor, his even being there creates conflict, and on a shallow note he makes for an American surrogate, which I think the studios will want to see. It has potential.
