In the Comic-Con 2011 trailer, what does Marduk (the epitome of the Scary Black Man trope, is literally as big as a bear (he stands at equal size and height to Kuma (an actual bear) and Jack-6), certainly out of the Tekken and Street Fighter casts) say to a gigantic, angry Hugo barrelling down on him? "That's big..." Then Hugo decks him in one shot with a clothesline. This troper cracked up.
What makes it funnier is that King simply carries on like nothing happened and acts like facing an 8-foot tall German wrestler that just barged in and clotheslined your friend is just another typical day for him.
Just Marduk meeting Poison. He's got the goofiest look on his face and he doesn't know about Poison's Viewer Gender Confusion.
The funniest thing out of all of this is that King literally pulled off a Squash Match victory against arguably the biggest fighter on the Street Fighter side and his manager. Come on, save for two cheap shots on Marduk, Hugo and Poison never got any offense on King, who proceeds to utterly wreck them. Crosses over with Crowning Moment of Awesome.
Some characters make not-so-subtle references to Poison's Viewer Gender Confusion. Ryu once even got away with a dick joke, though understandably, that one had to go (it was a veryOut of Character moment, anyway); it remains to be seen if any other characters have had their lines changed.
Kuma knows Poison's "secret" by scent. And concludes that Humans Are Weird.
When one activates Pandora, one starts to glow purple, get red eyes, etc. while sacrificing their partner. If Heihachi activates Pandora, he freaking kicks his teammate out of the battle and his skin turns red (like how a cartoon character would show that they're pissed off). This just shows that Heihachi doesn't even need the power of Pandora to go all Superpowered Evil Side on his enemies (and somewhat incompetent partner) and kick their ass. He just needs to be pissed off. So in general, Pissed-off Heihachi = Pandora Anyone Else. The funny part is how downright hilarious Heihachi looks when he's in Pandora compared to the Nightmare Fuel-esque Pandora forms of other characters.
Speaking of Heihachi, his in-game character model has caused some laughs due to his resemblance (as a result of the art) to Dr. Wily.
Juri/Bison's intro also qualifies. Juri acts like she's flirting with Bison note Who, mind you, killed her entire family and turned her into the psychopath she is thanks to the emotional trauma. over killing their opponents, and he just shrugs her behavior off like it's another Tuesday for him. And Bison's taunt IS "For me, it was a Tuesday."
To twist the knife further, in the US, the game literally came out on a Tuesday.
In Heihachi and Kuma's ending, Heihachi decides to pop open Pandora, all while Kuma is doing his best to tell Heihachi to leave it alone. Seconds later, when Heihachi ends up releasing the energy of the box, Kuma turns into a bear cub, as Heihachi (who's hair is partially black, ala Tekken 2) complains on how screwed he is.
In Abel and Guile's ending, a flying saucer appears, dropping several Kuma-esque aliens into the box. Seeing and hearing Abel's reaction as well as Guile's "the hell is wrong with him, Screw This, I'm Outta Here!" attitude when the aliens drop.
The Rolento/Ibuki team up is pretty hilarious, with Rolento being The Comically Serious, calling Ibuki "priviate" during the arcade mode, while Ibuki is exasperated about the whole arrangement.
Cole winning against Heihachi:
Cole: Stay out of this, gramps. Go eat some oatmeal or something.
We also have these gems against other characters:
(vs. Mega Man): You look like your closet threw up on you.
(vs. Bob): You're like a walking target. I'd have to try to not his you.
The Zangief/Rufus ending. In it the two are engulfed in a light from the box. When the light clears, Zangief's muscle and Rufus' body mass has been removed, effectively turning the unlikely team into a pair of much thinner guys with facial hair. Naturally, they cry in anguish at the loss of their perfect bodies.
When Law gets sacrificed in order for his partner to enter Pandora Mode, Law simply whines "I'm getting old!"
During Guile and Abel's duo intro, Abel steals Guile's line "Mission Start." The look on Guile's face is priceless.
These win quotes from Jack-X:
(vs. Sakura): A human under the age of 18 confirmed to be on the battlefield. Sending report to target's parents and guardians now.
(vs. Blanka): Target contains an estimated 150,000 volts of electricity... Viable recharging station confirmed. Now recharging batteries.
(vs. Dudley): I thank you for your invitation. However, I am not able to consume tea.
Some characters say the darndest things when they are knocked out...
Law: "I GOTTA TRAIN MOOOOOOOOOOOORE!"
Paul: "I DON'T UNDERSTAND!"
Bob: "MY PERFECT BODYYYYYYYY!"
Lei: "THIS STIIIIIIIIIINKS!"
Juri: "DAMN IT! NOOOOOOOO!"
Balrog: "MY FIGHT MONEEEEEYYYY!"
Asuka: "NOT FAAAAAIIIIIRRRR!"
During one of Bryan and Jack-X's cutscenes, Jack-X asks Bryan what he should call him. Bryan tells him anything at all. Jack then picks out a name for him - Jane.
In Alisa and Lars' ending, Lars attempts to destroy the Box by punching it. When that fails, Alisa uses her head and tosses it on the box, destroying it in an explosion. Lars' shocked expression to Alisa as she happily claps at her accomplishment is hysterical.
Xiaoyu's win quote against Guy shows her never having heard of the art of Bushinryu before. So what does she conclude it to be? A B-Tier Boy Band.
Alisa's normal forward throw is, as ever, handing her disembodied head to her opponent and it exploding in their hands. So what happens if the opponent manages to Throw Escape from it? They plop it right back on her neck stump! It doesn't explode but she does look ever so foolish thanks to her famous trick being beaten like that.
Dudley's intro. He is just having tea in the garden as usual when Elena appears telling she was summoned there by a tree that Dudley transplanted from Africa, and that the tree is telling them to go to Antartica to investigate Pandora's Box. Dudley doesn't even bat an eyebrow at how ridiculous that seems and just agrees to go with it as long as he can return in time for his title match.
Some of the alternate costumes are hilarious. Barring Mega Man, Pac-Man, Cole, and the cats, each fighter has a 2nd costume that's based on a character from the opposing franchise and a 3rd costume that has a random theme. However, Kuma's costumes are the most absurd. He's dressed as R. Mika of all people for his 2nd costume and his 3rd is him inside of a teddy bear costume. JACK-X is a close second with his E. Honda costume for his 2nd and resembling a vintage toy robot for his 3rd.
And because you can change the colors of the fighters' clothes, costumes, and skin in many different combinations, you can make them look like characters from completely unrelated material. For example, here's an image of Lei in his 3rd costume resembling Buzz Lightyear and here's one of Paul in his 3rd resembling Cap'n Crunch.