Three weeks has passed since Thanos erased half the universe thus leaving the other half alive to thrive causing everybody to recover slowly and gather everything where everybody vanished.
Dream Land
Kirby and his allies are preparing to board the Halberd to search for Carol Danvers to meet the Avengers, who are on Earth hunting for Thanos who left Wakanda after snapping his fingers and erased half the universe.
King Dedede: Well from the looks of it. I wonder if Sword Knight and Blade Knight could pilot the ship by traveling into space?
Kirby: They can! They will pilot it by going to hyperspace from galaxy to galaxy just like in the other movies like Star Wars for example.
Prince Fluff: Now it's designed to go into outer space! Wouldn't you say so!?
Chaise: It sure is how we have got to introduce ourselves to this Carol lady.
Gooey: Indeed!
Kirby notices both Susie and Francisca arriving.
Susie & Francisca: Hey, Kirby!
Kirby: Susie, Francisca! Long time, no see! How's it going?!
Susie: I could ask you the same thing! Half of all life disappeared before our very eyes.
Francisca: I saw both Flamberge and Zan Partizanne vanish. But Hyness and I survived that massive genocide.
King Dedede approach to the two.
Susie: Hey I've heard a lot about you! You're King Dedede! My name is Susie!
King Dedede: Nice to meet you, Susie! (to Francisca) It's been a while since we've clashed. Are you okay?
Francisca: Well sort of okay!
Carrie: Hi, I'm Carrie!
Ribbon: And my name's Ribbon!
Gooey: I am Gooey!
Chef Kawasaki: The name's Chef Kawasaki!
Susie: Pleasure to meet you!
Francisca: Me too!
Kirby: And the fact is that we're going to outer space and head on down to Earth.
Everyone: Yeah!
As soon Kirby and his allies board the Halberd. However, unknown to everybody, Marx emerges from a bush to board the ship, which is heading to Earth.
Marx: Hey, you guys, wait for me!
He made his way in before the doors could close behind him.
Marx: Whew! That was definitely a close call.
The Halberd's engines fire up and getting ready for take off.
Kirby arrives at the bridge, where Sword Knight and Blade Knight are piloting to search for the location of planet Earth, where the humans live.
Sword Knight: Any suggestions, Kirby?
Kirby: We find Carol.
Blade Knight: Affirmative!
They take off for outer space right before going into hyperspace.
Somewhere in space
On board the Benatar, Tony Stark a.k.a. Iron-Man and Nebula playing paper football when Nebula catches the paper football.
Nebula: Wrra! [Nebula, frustrated, puts her hands in a fighting stance while looking at Tony.]
Tony: You don't need to do that. Because uh... you're just holding position. [Nebula flicks a paper football towards Tony] Oh yeah, that was close. [Nebula once again flicks a paper football towards Tony] That's a goal. We're now one apiece.
Nebula: I would like to try again. [Nebula flicks a paper football towards Tony]
Tony: We tied up. Feel the tension? It's fun.
[Tony poorly flicks a paper football towards Nebula]
Tony: That was terrible. Now you have a chance to win. [Nebula flicks the paper football towards Tony]
Tony: And... you've won. Congratulations. [Tony reaches his hand out to shake Nebula's hand]
Tony: Fair game. Good sport. [Nebula shakes Tony's hand] Have fun?
Nebula: It was fun.
[Camera switches to see Iron Man's busted helmet. Tony Stark's hand reaches forward to turn on the helmet. We pan out to see that he's sitting on the floor of a gloomy Benatar. The weight of the recent events of INFINITY WAR evident in Tony's posture. He taps the helmet with a sigh.]
Tony: This thing on? [The helmet scans Tony. Tony leans against the wall while taking deep breaths. He looks skinnier and weak with malnutrition.] Hey, Miss Potts... Pep. If you find this recording, don't post it on social media. It's gonna be a real tear-jerker. I don't know if you're ever going to see these. I don't even know if you're... if you're still... Oh god, I hope so. Today is day 21, uh 22. [Cut to Tony standing at a window to stare out in space, waiting for his impending doom to arrive.] You know, if it wasn't for the existential terror of staring into a void of space, I'd say I'm feeling better today. The infection's run its course, Thanks to the blue meanie back there. [Cut to a shot of Nebula sitting in the back of the Benatar.] You'd love her. Very practical. Only a tiny bit sadistic. Some fuel cells were cracked during battle, but we figured out a way to reverse the ion charge to buy ourselves about 48 hours of time. [A shot of Tony and Nebula working on the fuel cells of the Benatar.] But it's now dead in the water. We're 1000 light years from the nearest 7-11. Oxygen will run out tomorrow. And that'll be it. And Pep, I ... I know I said no more surprises, but I was really hoping to pull off one last one. But it looks like... well you know what it looks like. Don't feel bad about this. I mean, if you grovel for a couple of weeks, and then move on with enormous guilt. I should probably lie down. Please know that... when I drift off, I will think about you. Because it's always you.
[With that, Tony turns the helmet off. He rubs his thumb over the left eye, and then leans down, to what would be his last sleep. Nebula walks over to him, and carries him to Drax's seat, and lies him there. She walks away dejected.]
[A vast bluish nebula illuminates the space surrounding them. Cut to a shot of Tony's face, which for the first time shows age and weakness. There is a light on his face, which grows brighter and brighter until he's forced to open his eyes. The camera pans around to the light source, which is slowly revealed to be CAROL DANVERS.]
However, the Halberd emerges from hyperspace heading towards the Benatar. Carol, Tony, and Nebula look at the ship, which is being piloted by the two Knights, who had noticed Carol Danvers.
Sword Knight: Look, it's Captain Marvel!
Blade Knight: Hey, Kirby! We found her!
Kirby: Carol, I've missed you so much!
He comes out of the ship before he and Carol hug after 23 years.
Carol: Oh, Kirby! How I've really missed you?
King Dedede: Well that's a bitter reunion!
Prince Fluff: Tell me about it!
Kirby: So anyway! What happened to Fury?
Carol: Well the Avengers told me he's gone after Thanos snapped everyone away.
Kirby seems shocked about it.
Kirby: Oh, no! Not Fury!
Carol: It's okay! We'll figure this one out!
He nods.
Carol: Now let's get Tony back to Earth safe and sound.
Everyone in the Halberd nod in agreement.
Near New Avengers Facility, Forest Area, night
Somewhere in the forest, Knuckles and his team are waiting for Sonic and the others to arrive so they can meet the Avengers. But suddenly, both the Resistance and Jet's ships made it just in time so they can figure a way to take down Thanos.
Knuckles: Hey, Sonic! You guys, it's good to see you!
Sonic: Good to see you too, Knuckles! We think!
Amy: Tails, Cream, Blaze, and half the universe are gone.
Cheese: Chao, chao!
Silver: Cheese said his owner gone.
Rouge: So that's why he can't live without her.
Shadow: Also Tikal, Omega, Charmy, and Ray are too.
Jet: And now Wave and Storm as well.
Espio: Well it looks we're gonna have to meet our heroes face to face about this predicament.
Vector: I heard that you guys were in Wakanda to search for them. What's this all about?
Big: Well Sonic obtains some Vibranium shields that were used by Captain America after he dropped them.
Sonic shows them the Wakandan shields.
Sonic: Well Tails would have seen them if he upgraded them so I can take down some Eggman robots.
Amy: At any case! Their base is up ahead! We've gotta get going!
Jet: I'll meet up with you later! Lincoln said he and SpongeBob are going to see them as well.
Sonic: OK! You be careful, Jet!
He takes off in his ship.
Sonic: At any rate! Let's go!
They rush off to the base.
Highway, night
The turtles are arriving in Upstate New York, where the Avengers are located.
Don: Uh, guys! I think the highways are full of empty cars where people disappeared.
Leo: At any case! We should bypass the freeways and get to their base.
Mikey: I hope this bucket of bolts can fly us there.
Don: Well certainly!
He presses green button, which activates the truck's jet engines and it began to fly.
Raph: Now this is what I call flying.
Leo: Next stop: Avengers Compound.
Elsewhere in the Avengers Compound
In the bathroom area, a now clean-shaven Steve Rogers holding a blade, having just shaved off his beard. He sighs and looks into a side mirror. The mirror suddenly starts shaking, slowly at first, and then severely. Cut to the yard in the Avengers Compound, we see Steve Rogers, Natasha Romanoff, Bruce Banner, and James Rhodes walking out looking at something, the Benatar carried by Carol Danvers as she lands the spacecraft. The landing gears deploy as they touch down. The entry hatch opens, and Tony and Nebula walk out, Tony being supported by Nebula. Steve runs to Tony to help him stand up. Tony grips Steve's arm as he joins him.
Also the Halberd lands on the Hudson River, which the ship could destroy the base.
Natasha: What was that big ship?
Carol: It's called the Halberd!
Tony: I couldn't stop him.
Steve: Neither could I.
Tony: I lost the kid.
Steve: Tony, we lost.
Tony: Is, uh...? [Tony struggles to ask about Pepper.]
Pepper: Oh, my God! Oh, my God! [She and Tony embrace.]
Tony: It's okay.
Sonic and the Freedom Fighters arrive.
Sonic: Hi, you must be the Avengers?!
Steve: Hey, Sonic the Hedgehog! I've heard a lot about you a few years ago.
Bruce: And I've heard a lot about you, Knuckles! You're the guardian of the Master Emerald on Angel Island.
Knuckles: Pleasure to meet you, Bruce Banner!
Silver: You must be Tony Stark, the legendary Iron-Man?!
Tony nods.
Sonic: Tails is your biggest fan. I wish he was here known some of your tech.
Suddenly, the Turtle Tactical Truck lands next to the Benatar before the turtles step out of the truck.
Leo: It looks like we found them.
Mikey: Oh my! It's them! The Avengers! See, you guys! That's what I've been trying to tell you they're here! Also I'm a big fan of Scarlet Witch.
Raph: Yeah, yeah, Mikey! Don't get all too riled up!
Don walks up to Tony.
Don: Hey, it's the legendary Tony Stark. I like some of your tech.
Tony: Thanks. You must be Donatello?
He nods.
Leo: We're the Teenage Mutant Ninja Turtles.
Kirby walks up to the group along with King Dedede, Susie, Francisca, and Marx.
Kirby: Hey, Sonic!
Sonic: What's up, Kirby? Long time, no see! I haven't seen you since the last time we fought Galeem and Dharkon and saved the Smash universe.
King Dedede: Same here! I was there too, you know?!
Amy: From the looks of it. We have to help Mr. Stark get back to health.
Susie: We need get him in right away!
Espio: Roger that!
Vector: Oh I wish Charmy were here. He would rather fool around with his idiotic self.
Mighty: Ray would like this place if he was alive.
Shadow: There's no time for moping around, let's get going!
Rouge: Come on!
Rocket Raccoon sits down with Nebula and takes her hand, both silently mourning their losses of Groot, Star-Lord, Gamora, Drax, and Mantis.