Here is the scene where everyone goes to Karaoke night and Ash and Serena sings You'll Be in My Heart goes in War of the Apocalypse.
(Cut to the heroes made it to Karaoke)
Emerl: This is it, Karaoke!
Xion: It's going to be so nice!
Tino Tonitini: Let get in there!
(Later everyone are inside the Karaoke bar)
Screeno: Ladies and Gentleman, Get your Karaoke set up!
Emerl: This is so excited.
Sunset Shimmer: I can't wait for that, boyfriend.
Tino Tonitini: Me, too, babe.
Sora: You say something?
G-Merl: Oh, uh... nothing.
Tino Tonitini: So what are you guys going to sing?
Ash Ketchum: Well, Serena and I could sing one song together.
Serena: I think I found it.
Ash Ketchum: What is it?
(They see the writing that says Phil Collins - You'll Be in My Heart)
Serena: I found our favorite song we always sing.
Ash Ketchum: Alright. Let's go for it as soon as everyone are done singing in the performance.
Camsta: Come on, Let's do it!
Mimi Tachikawa: Let's make this dream come true!
Tino Tonitini: Hey, Sunset Shimmer, I've found a good song to sing.
(They see the writing that says Dani Marcus - Open my Eyes)
Sunset Shimmer: Wow! This will be perfect. We'll go before Ash and Serena are next.
Zoe Drake: Then let's get this Karaoke going!
(Later everyone are watch their friends singing their songs like Mordecai and Rigby sings "Twisted Sister - We're Not Gonna Take It", next Pops sings "Kenny Loggins - Footloose", then Carver sings "Michael Jackson - Man in the Mirror", then Lor and Tish sings together "Jheno - W.A.Y.S", Sora Takenouchi sings "Carley Rae Jepsen - Call Me Maybe" and at last Tino and Sunset Shimmer sings "Dani Marcus- Open my Eyes")
Myke: Alright, that's all of the singers in Karaoke.
Camsta: Okay, now the last singers will in the final stage.
Screeno: Now everyone let's give it up for... Ash Ketchum and his Girlfriend Serena!
(Everyone cheers as Ash and Serena walks to the stage and picks up their microphones)
Ash Ketchum: Thank you, everyone. And we're gonna sing a song.
Serena: And it's called "You'll be in my Heart". I really hope you enjoy our date.
Tai Kamiya: Come on, guys sing!
Agumon: Go for it!
Tino Tonitini: Sing! Sing!
All: (Chanting) Sing! Sing! Sing! Sing!
(Phil Collins - You'll Be in My Heart plays)
Ash Ketchum: Come stop your crying it will be alright. Just take my hand, hold it tight. I will protect you from all around you I will be here don't you cry.
Serena: For one so small. You seem so strong. My arms will hold you keep you safe and warm. This bond between us can't be broken I will be here don't you cry.
Ash & Serena: Cause you'll be in my heart. Yes, you'll be in my heart. From this day on now and forever more. You'll be in my heart. No matter what they say. You'll be here in my heart, always.
Ash Ketchum: Why can't they understand the way we feel.
Serena: They just don't trust what they can't explain.
Ash Ketchum: I know we're different but deep inside us. We're not that different at all.
Ash & Serena: And you'll be in my heart, yes you'll be in my heart. From this day on now and forever more.
Serena: Don't listen to them, cause what do they know.
(Ash: What do they know)
Serena: We need each other, to have to hold.
Ash & Serena: They'll see in time, I know.
Ash Ketchum: When destiny calls you, you must be strong.
(Serena: You gotta be strong)
Ash Ketchum: I may not be with you, but you got to hold on. They'll see in time, I know.
Ash & Serena: We'll show them together cause. You'll be in my heart. Believe me you'll be in my heart.
Serena: I'll be there.
Ash Ketchum: From this day on now and forever more.
Serena: Ooh, you'll be in my heart.
(Ash: You'll be here in my heart)
Serena: No matter what they say.
(Ash: I'll be with you)
Ash & Serena: You'll be here in my heart! I'll be there always. Always.
Serena: I'll be with you.
Ash Ketchum: I'll be there for you always, always and always.
Ash & Serena: (x3) Just look over your shoulder. I'll be there always.
(Then the song ends as Ash and Serena makes a heart shape on their hands to each other and everyone applause and cheer)
Benson: Yeah-heah! Alright!
Rod: You two love birds rock!
Ed: Aw. Isn't that sweet?
Rika Nonaka: That song is so amazing!
G-Merl: Way to go, you two!
Muscle Man: (Whooping) That was awesome!
(Ash and Serena walk off the stage and back to the group)
Tino Tonitini: Awesome singing!
Ash Ketchum: Thanks!
(Pikachu runs to Ash and hugs him)
Ash Ketchum: You like it how Serena and I sing, buddy?
Serena: I'm glad you love that song we always sing!
Mordecai: Let's go home. I need some sleep.
Rigby: Me too.
Emerl: Alright, let's go home. Tomorrow we're going to florida.
Tino Tonitini: Sounds like a great idea!
Michelangelo: That is so sweet!
(They got out of the Karaoke and walk away to Hiatt Grey's beach house. Later Ash and Serena are in their bed together as Ash turns off the light)
Ash Ketchum: Good night, Serena.
Serena: (Yawning) Good night, Ash. Sweet dreams.
Ash Ketchum: (Yawning) Sweet dreams to you too.
(They close their eyes and falls asleep)