Here is how Sunset writes to Twilight, Joker, Harley, and the Bowser Family try to stop Twilight and Spike, and the Guardians of the Galaxy arrive in Code Red's Adventures of My Little Pony Rainbow Rocks.
(we see the girls outside the school)
Human Fluttershy:(lets a lady bug on her finger) I can't believe they got to Principal Celestia and Vice Principal Luna too.
Human Rainbow Dash: They've gotten to everybody!
Human Pinkie Pie: Not everybody.
Human Applejack: Pinkie Pie's right. We were there when the Dazzlings were singing and we weren't effected. It was like we were protected somehow.
Human Rainbow Dash: So let's take them down! It's not like we haven't tangled with dark magic before and whooped its sorry but!
Sunset Shimmer: Yep.
Human Fluttershy: But that was when Twilight and Code Red were here. There may be some kind of magic inside us, but it only comes out when we play music. I sure don't know how to use it to... whoop anybody's but.
Human Rarity:(sighs) If only we could get a message to Twilight. Maybe she can tells us how to break the spell the Dazzlings have put on our friends.
Human Rainbow Dash: Well that's not gonna happen.(kicks the ball against the mirror) The portal's closed.
Human Rarity:(gasps)(gasps again)
Human Rainbow Dash: And I don't think they have cellphone in Equestria.
Sunset Shimmer:(remembers something) I think I know how to contact princess Twilight.
Sunset Shimmer: When I was Princess Celestia's student in Equestria, she gave me this. Even after I abandoned my studies, I held onto it. I guess I knew I was making a big mistake, and I wanted a way to reach out to her. Maybe it still works.
Human Rarity: That's a book, darling. What do you mean, "maybe still works"?
Sunset Shimmer: It used to be that if I wrote something here, it would appear in the pages of a book back in Princess Celestia's library. I get a message to her, then she can get a message to Princess Twilight.
Human Rainbow Dash:(holds out a pen) So what are you waiting for? Get to writing!
Sunset Shimmer:(takes it) It's been a long time since I've written these words. "Dear Princess Celestia.".
(the writing glows and goes through a swirling portal)
(we see the Mane 6 doing things)
(outside the Castle of Friendship)
Joker: The Dazzlings can't have any interference.
Azula: I know. Which is why we're going to get rid of them.
Other Sucicide Squad members: What?!
Killer Croc:(to Harley) You're in on this?!
Harley Quinn: Yeah, so what?
Crossbones:(grabs her by the neck)
Taskmaster:(puts his sword against Azula's neck) Not on our watch.
Mistress 9: I think not.(presses a button that knocks them out)
(not far away from them, are five figures standing by a very familiar ship)
Figure 1: So you sure you know what you're doing Quill.
Figure 2: Of course Rocket. I know what I'm and we're doing.
Figure 3: What if it gets us arrested?
Figure 4: Drax is right. What then?
Figure 5: I am Groot.
Figure 1: It's decided. Let's go kick some villains but.
(inside the castle)
Spike: But I still get to go right? There aren't any of me in Canterlot High.
Joker: I'm afraid not.
(they turn to see the villains)
Pinkie Pie: And the other villains!
Dragaunus: I hope you're ready to be destroyed.
???: I don't think so.
Koopa Troopa:(turns only to be thrown out of the room by a giant walking tree)
Rocket Racoon:(takes out his gun) You guys ready to start runnin' and leave or what?
(Joker takes out his gun)
Gamora:(cuts it in half)
Joker: I surrender!(throws up his hands)
Gamora: Nice try.(kicks him in the face, knocking him out)
(Drax picks up Dragaunus)
Drax the Destroyer:(throws him)
Bowser: Brother, NO!
Rainbow Dash: This is awesome!
Mistress 9:(to Quill) Who do you think you are?!
Peter Quill(Star-Lord): I'm Star-Lord.
Bowser Jr.:(in Korath's voice) Who?
Peter Quill(Star-Lord): I'm Star-Lord man.
Drax the Destroyer: You ready to run yet.
Bowser: As a matter of fact, yes.
(they run out of the castle)
Rainbow Dash: That was totally awesome!
Fluttershy: Yes! That was amazing!
Rocket Racoon: Thank you. You're all amazing too.
Applejack: Just who the hay are y'all?
Peter Quill(Star-Lord): My name is Peter Quill, the half Terran from Earth. I'm also known as Star-Lord.
Gamora: The name's Gamora. I'm one of the deadliest assassins in the universe.
Rocket Raccoon: I'm Rocket, and there ain't nothing like me, cept me.
Fluttershy: Aw, he's so cute.
Rocket Raccoon: I'm not cute.
Drax the Destroyer: I am Drax the Destroyer.
[the tree man walked up to them]
Groot: I am Groot.
Fluttershy: Really? That's interesting.
Rocket Raccoon: so you're goin' ta Earth, huh?
Twilight Sparkle: Yep.
Drax the Destroyer: We're going as well.
Spike: You sure? What if there are counterparts of you there?
Rocket Raccoon: There aren't counterparts of us there.
Rainbow Dash: And how do you know that?
Rocket Raccoon: Cause Mr. Quill here is from that world.
Twilight Sparkle: Alright. Let's go. See you on the other side.
[they go into the portal]
(screen goes black)
Deadpool:(appears) Be sure to like, fav, and subscribe.(leaves)