It was a normal day at the S.H.I.E.L.D. Helicarrier...
IRON MAN: Yeah, then I put Mandarin in jail.
SPIDER-MAN: Woah! Cool!
CAPTAIN AMERICA: -snorts- Not as cool as what I did to Red Skull.
HULK: OOOOH! Hulk smell challenge!
FALCON: So, Cap, what was so AMAZING you did to Red Skull?
CAPTAIN AMERICA: I pushed him out of the plane and he fell to his death.
HAWKEYE: DUDE. That's cold!
THOR: He survived, by the way.
CAPTAIN AMERICA: I'm sorry?
THOR: Yeah. He landed in the Alps and found the Tesseract, then it teleported him to Odin's Throne Room.
IRON MAN: Hah!
NICK FURY: GUYS GUYS WE GOTTA EMERGENCY!
CAPTAIN AMERICA: We gotta emergency? I think you mean "We've got an emergency,"
SPIDER-MAN: Grammar nazi.
CAPTAIN AMERICA: Hey, I'm not a Nazi.
NICK FURY: The X-Men and the Fantastic Four wish to see you at Palm Beach in Florida.
BLACK WIDOW: What? But it's so far away...
NICK FURY: I don't care! AVENGERS ASSEMBLE!
Meanwhile, at Palm Beach in Florida...
WOLVERINE: The X-Men are awesome!
BEAST: Yeah! We rule!
HUMAN TORCH: No way, man! Fantastic Four are better!
THE THING: You bet we are!
CYCLOPS: Every girlfriend I have dies.
The Avengers arrive...
THOR: What seems to be the problem, fellow superhero teams?
WOLVERINE: We'd like to challenge you to a battle of the ages.
IRON MAN: Really? What for?
MR. FANTASTIC: To find out which superhero team is the best in this universe!
HUMAN TORCH: No contest, it's the Fantastic Four.
PROFESSOR X: Incorrect! The X-Men are superior to you!
IRON MAN: Uh, the Avengers PWN you all.
FALCON: What he said.
BEAST: Yeah? Well, let's all fight for it!
PROFESSOR X: Indeed. The X-Men VS The Fantastic Four VS The Avengers. Let the battle commence!
Everyone splits up in their own ways to their "base"
WAR MACHINE: So me and Falcon will guard the base camp boundary?
CAPTAIN AMERICA: Yup! Good luck! -runs out of the base camp with Iron Man, Hulk, Thor and Black Widow-
Meanwhile, at the X-Men base...
WOLVERINE: Ready to go into battle?
BEAST: You bet! Nightcrawler, you coming?
NIGHTCRAWLER: -shakes head yes-
CYCLOPS: Well, let's get moving. Professor X is gonna be our Oracle, right?
WOLVERINE AND BEAST: Our what?
CYCLOPS: Oracle! He communicates with us through communicating devices or something.
BEAST: Sure, why not?
Wolverine, Nightcrawler, Beast and Cyclops leave the base. And meanwhile, at the Fantastic Four base...
MR. FANTASTIC: Alright, are we ready to go?
INVISIBLE WOMAN: Yup! Silver Surfer, you guard the base.
SILVER SURFER: Yeah, okay.
All the teams meet up in the center of the beach and start battling
NICK FURY: STOP! Everyone knows that S.H.I.E.L.D. is better than all of you guys put together!
IRON MAN: What? No way!
THING: You guys are stupid.
CYCLOPS: Guys, wanna team up and defeat S.H.I.E.L.D.?
BEAST: What would our team name be?
SPIDER-MAN: How about The Spider-Men?
BLACK WIDOW: No, you idiot! There are girls here.
BEAST: How about X-Men Unlimited?
CAPTAIN AMERICA: Some of us aren't mutants.
IRON MAN: I got it! The Ultra-Avengers!
EVERYONE EXCEPT S.H.I.E.L.D.: Yeah!
NICK FURY: Okay, guys, BRING IN THE S.H.I.E.L.D. AGENTS!
Phil Coulson, Maria Hill, Sharon Carter, Jasper Sitwell, Luke Cage and the guys from the TV show "Agents of S.H.I.E.L.D." show up
PHIL COULSON: Attack!
IRON MAN: Tank missile! -shoots them and the S.H.I.E.L.D. base blows up-
BEAST: We did it!
WOLVERINE: Party at my beach house?
Meanwhile, at the beach party...
HUMAN TORCH, IRON MAN, WOLVERINE, AND SPIDER-MAN: -doing the Harlem Shake at the party-