I don't own Avengers: Earth's Mightiest Heroes, Wolverine and the X-Men, and their related characters. I just own Mass Extinction and Thunderstorm.
Thunderstorm was relaxing with her sister Mass Extinction after the latter escaped from the Weapon X facility but she she saw a black haired teenage girl and redheaded teenage girl getting chased by some tanks and trucks with the letters MRD on the sides. She said, "Great those maniacs are chasing a couple of innocent girl." The shapeshifter just turned into a passenger pigeon and the thunderstorm powered girl took to the air and flew in between them and then Mass Extinction turned into a Therizinosaurus and with Thunderstorm which blocked their view of the girls, turned their heads, and told her "We're here told help you." The two young teenage girls just nodded as the dinosaur just slashed at the nearest truck with flaming claws. She the looked at the MRD men and said, "I should thank the people of the Facility because they made me more versatile." Thunderstorm fires bolts of lightning. Mass Extinction then turned into a Cryolophosaurus and froze them solid with icy Antarctic breath. Mass Extinction finally turned back into a human and they tell the girls hello. As they were greeting the girl the ice just broke and the MRD men were free and ordered the tanks to fire as Mass Extinction turned into a Aerosteon and blasted the tank rounds with a power blast of wind but she missed two as it was about to hit her and Thunderstorm. The black haired girl destroyed it with a blast of fireworks, the redhead destroyed the other with a blast of microwave radiation, and Mass Extinction and Thunderstorm said, "Thank you". Finally the X-Men showed up and a short man with claws came out of the jet, saw the black haired girl and the younger redheaded girl, and said, "You want to come with half pints."They turned to Mass Extinction and Thunderstorm and asked, "Should we go with him? Our names is Jubilation Lee and Angelica Johnson by the way." Mass Extinction and Thunderstorm said, "Yes, go with them and good luck Jubilee and Firestar." Jubilee and Firestar followed Wolverine into the Blackbird and thanked Mass Extinction and Thunderstorm. The two sisters said, You're welcome and goodbye." The sisters waited for the Blackbird to leave and then Mass Extinction turned into a Carolina parakeet and flew off while Thunderstorm rode the winds and flew with the bird.
Mass Extinction said to Thunderstorm, "We need to research the super heroes, super villains, and others like them. They went to a computer and using the super intellect of Mass Extinction's Gigapithecus form and started doing research and said, "Captain America, Iron Man, Thor, Spider-Man, Wasp, Ant-Man, Hulk, Black Widow, Hawkeye, Mockingbird, War Machine, Quake, Falcon, Professor X, Wolverine, Shadowcat, Beast, Iceman, Rouge, Jean Grey, Cyclops, Forge, Angel, Colossus, Nightcrawler, Storm, Luke Cage, Iron Fist, Mr. Fantastic, Invisible Woman, Human Torch, Thing, Black Knight, Captain Britain, Black Bolt, She-Hulk, Daredevil, Punisher, Deadpool, Elektra, Living Laser, Mandarin, Wendigo, Baron Zemo, Grim Reaper, Klaw, Mandrill, Red Ghost, The Super Apes, MODOC, Techovore, Purple Man, Cobra, Death Adder, Constrictor, Anaconda, Bushmaster, Cottonmouth, Diamondback, Grey Gargoyle, Leader, Abomination, Zzzax, Vapor, Ironclad, Vector, X-Ray, Radioactive Man, Madman, Absorbing Man, Wrecker, Thunderball, Bulldozer, Piledriver, Excavator, Bulldozer II, Crimson Dynamo, Magneto, Quicksilver, Blob, Toad, Domino, Avalanche, Chemistro, Whiplash, Bushman, Sphinx, Whirlwind, Baron Strucker, Viper, Arnim Zola, Reptyl, Blizzard, Griffin, Mad Thinker, Sandman, Hydro-Man, Doctor Octopus, Electro, and Kingpin." They didn't read the whole files because SHIELD's systems went down.
Mass Extinction turned into a Meganeura flew at super speed to the Helicarrier with Thunderstorm using the winds to make her fly faster. When they got there the Big House enlarged and caused the Helicarrier to crash into the New York Bay. Then they turned and saw some guy in blue fighting Thor.
Back at New York harbor, Ant-Man and Wasp ask Fury. Who is that guy? Fury said, "That is Franklin Hall." Hank recognizes the name as the physicist who disappeared after joining SHIELD. In the skies above, Thor begins attacking Graviton, but can't get through his shield. Graviton then hurls Thor away from him and again Thor attempts to throw Mjolnir at Graviton but was deflected by his shield. Mass Extinction turned into a Quetzalcoatus mid flight and tried to jab him with her beak but got thrown into the bay. Thunderstorm also gets thrown in the bay Mass Extinction simply shapeshifted into a Wiwaxia which changed her size and threw off the effect of Graviton's gravity powers and turned into a Mauisaurus and swam back to the surface.
In Nevada, The Hulk crashes into the Vital Sign Diner with Samson. The Hulk tells the waitress to get him some soup and take care of him. The Hulk hears the voice of Banner inside him, telling him that he could help them, that he could save Thor. The if he begins to help others and save lives, people will see that The Hulk isn't a monster. The Hulk tells Banner that he wants something in return. He wants to stay as Hulk all the time.
Above the harbor, Thor continues striking at Graviton, and the Wasp and Mass Extinction decide they have to do something to help stop him. Wasp shrinks down and flies out to the battle and Mass Extinction turns into an Archeopteryx and flies alongside Wasp, just as Graviton increases the force of gravity on Thor, sending him to the bottom of the sea. At the bottom, Thor begins to sink into the silt with Mjolnir out of reach. Graviton then begins flying towards shore, screaming for Fury. The Wasp begins to fire her stings at him with Mass Extinction fires feather fletchettes stopping him momentarily. He sends them flying away, just as Iron Man arrives. He slams into Graviton and sends him flying into the water with a repulsor blasts. Graviton resurfaces and JARVIS said, "Graviton's energy output is as comparable to a black hole." Graviton agrees, and sends Iron Man hurling into outer space.
On shore, Pym asks, What Graviton's upper limits are?" Fury tells him that they studied him for years and as far as they can determine, he doesn't have any. Hank then presses a stud on his belt, and begins growing. He slams Graviton between his hands, but is just sent hurling away as well. As his feet are dragging on the ocean floor, it uncovers Thor and Thunderstorm, who begin clawing their way back out. Graviton finally confronts Fury, and says that he's going to destroy him, and then the city. Graviton pulls him up and begins crushing him, only to reveal that it's not Fury at all, but an L.M.D. Enraged, Graviton begins flying towards the city, and causing random destruction. He then begins exercising his power fully, and lifts the entire island of Manhattan into the air.
As Graviton is examining his handiwork, he notices Thor and Thunderstorm and just manages to block their first blows, but their second blows sends Graviton reeling. Without his support though, the entire landmass begins crashing back down. Thor flies underneath to try and slow it's decent, and manages to get it down without total destruction. Thor then frees himself from underneath, and flies back to the surface.
Out in space, Iron Man is trying to get back to the Earth but without any effect, and keeps getting further and further away. Just as Thor and Thunderstorm knocked Graviton back, his effect on Iron Man stopped, and Tony rocketed back to the planet.
Graviton is back above land, and trying to destroy it some more, when he is struck by Mjolnir again, sending him crashing into the ground. Graviton rises, and just as he's about to attack Thor, he is struck down again, but this time by Iron Man's unibeam. As Graviton is digging himself out, Giant Man, Wasp, Thunderstorm, and Mass Extinction arrive as well, telling him he should stand down. Enraged, Graviton lashes out, sending them all crashing into the surrounding buildings, pinning them there. He begins screaming about his power and that he is the strongest one there is. Just then, The Hulk arrives and said, "He shouldn't be too sure about that." Hulk then slams into Graviton and begins pounding on him relentlessly. They go flying off into the docks, and the Hulk keeps knocking Graviton around with the shockwaves of his poundings.
Graviton gets a second to compose himself, and that's all he needs. He sends the Hulk sinking into the ground, and as the other heroes try to attack, he does the same to them, pinning them all down into the ground. Graviton begins rejoicing in his own power, enraging the Hulk. The Hulk then begins to pull himself up and out, inch by inch. Each time Graviton sends him crashing down, the Hulk pulls himself up again. Giant Man shrinks down to ant size, and begins ordering all the nearby ants to attack Graviton. Graviton, noticing the power of the Hulk, begins to worry and states that nothing is that powerful. Graviton then sends all the surrounding containers at the Hulk, burying him. Just then, one of the ants stings him on the back of the neck, and the others begins swarming around him.
His concentration broken, the Hulk bursts out of the containers and slams into Graviton. The other heroes are freed now as well, and begin flying towards the battle. Graviton sends the Hulk hurling hundreds of feet in the air, and then sends the containers flying towards him. As Iron Man begins firing pulse bolts at Graviton, his concentration is broken again, and the Hulk begins falling towards the containers coming up at him. Just then, Wasp flies at his shoulder and begins blasting a pathway for him back towards Graviton. Shocked, Hulk realizes that she's helping him, and she tells him "Yeah. Now hit him" With a grin on his face, the Hulk does so gladly, slamming into Graviton and driving him deep into the ground.
Graviton sends massive tons of earth, hurling the Hulk away. As Iron Man begins attacking with his unibeam again, Graviton does the same to him. Ant-Man then heads out to the water, and diving into it, increases his size, and hurls a cargo ship crashing into Graviton. Mass Extinction turns into a Dikelocephalina and fired a bolt of lightning. Thunderstorm pelts him with hail. Thor, flying high above, summons his birthright, and focuses all his power through Mjolnir, striking Graviton and frying him.
Looking down at Graviton drooling on himself, Hulk asks him "Who's strongest now?". Thor tells them that they should go celebrate, when SHIELD arrives. Quartermain orders them to step away from the Hulk, and that he's a fugitive from The Cube. Iron Man steps in front of his line of fire and tells him that if they want The Hulk, they'll have to go through him. The other heroes do the same, while Tony tells them that Hulk saved them all and that he's a hero. Nick Fury steps up and orders all the SHIELD agents to stand down, that they have bigger problems. He tells them that there is now seventy-four super-villains on the loose all across the country. He tells them that they should all come work for him, that together they can stop them all and make a real difference. Hank tells him no, that Graviton is his fault. SHIELD kept him under wraps, and then all this happened. Iron Man says that Fury is right, but not about working for SHIELD. There's no way that they could stop that many super-villains working alone, but together they could change things. They could avenge all the wrongs done by the villains, and they decide to team together as the Avengers. Quartermain then approaches Fury and tells him they've recovered the footage. The power failures and subsequent breakouts happened before Graviton got loose. Someone else is to blame.
Together, we have a chance. What we did here, it can change things. The world needs us, but not as SHIELD agents; as a team, on our own. Together, we can avenge the wrongs caused by all these villains. Wasp then said, "We can be Avengers." Hulk then said, "Good name." Mass Extinction and Thunderstorm agree with what was said.