This is how Optimus' castle and Let the Rainbow Remind You goes in My Little Pony Transformers Prime: Optimus' Kingdom.
[They stare at the castle wide-eyed]
Rarity: Sweet Celestia! Are you all seeing what I'm seeing?
Bumblebee: [beeps] (translation: Yes!)
Twilight Sparkle: A castle.
Optimus Prime: But... whose is it?
Princess Celestia: I believe it is yours, Prince Optimus.
[Optimus is suprised]
[
Princess Celestia: You've been wondering what you are meant to do as a prince. Do you know now?
Twilight Sparkle: Yeah.
Optimus Prime: As prince, I believe I have the power to spread Autobot and Equine friendships across Equestria. That is the role I am meant to have in our world! The role I choose to have! But I didn't defeat Thunderwing on my own – it took all of us to unlock the chest!
Princess Celestia: Then it is unlikely you are meant to take on this task alone.
Main cast: [gasping in awe]
Pinkie Pie: Wowee!
Smokescreen: Awesome.
Princess Celestia: You are now Optimus Prime, the prince of Cybertronian Friendships. But what is the prince of friendship without his friends?
[The others smile]
[Optimus sees Pythor being left of the group and decides to bring him in]
Pythor P. Chumsworth: Wait a minute, where's my throne?
Twilight Sparkle: I don't think you're quite there yet.
Princess Celestia: Because of your betrayal.
Pythor P. Chumsworth: [chuckles] Yes, well I suppose not.
[Let The Rainbow Remind You starts playing]
Optimus Prime and Twilight Sparkle: Each one of us has something special~
That makes us different, that makes us rare~
Ratchet and Fluttershy: We have a light that shines within us~
That we were always meant to share~
All: And when we come together~
Combine the light that shines within~
There is nothing we can't do~
There is no battle we can't win~
When we come together~
There'll be a star to guide the way~
It's inside us every day~
See it now! See it now!~
Let the rainbow remind you~
That together we will always shine~
Let the rainbow remind you~
That forever this will be our time~
[The song continues as a ceremony is held]
[Pythor, Celestia, Luna, and Cadance sit together. Pythor then uses his tail to hold up bouquets to Celestia, impressing her. Celestia then smiles at Pythor, who winks at her as she winks back]
Optimus Prime and Twilight Sparkle: Let the rainbow remind you~
That together we will always shine~
[