Here is the song I personally created. If you want to help me create this song for real, sign in the comments. I did changes who are with season 3 and personal changes who I think would have been better. If you have any questions, ask them.
The ballad of Marco Diaz
Who is the guy with the brownish hair?
Who sleeps on soft beds and dances on magic waves
With tears made of cheese and a heart full of safeness
Whose infinite gains are known near and far
It's Earth’s own sweetheart, our dear Princess Marco
And under the dress and makeup and petticoats
Lies hidden a strong and extreme boy
The forces of evil that roam in the school
Will kneel in fear when this dark luminary...
Weaving weapons like a born soldier
And destroys damages like a safe disaster
He rocks his dimensional scissors and karate
He is going to earn his status, so hail to the princ-ee-e-ss-s!
'Cause he's a rebel princess, he's the best
He’s a ball of fire in a large purple dress
He’s a storm roaring through the stars
He’s our dark luminary, and he's lighting up the night!
[slow, heavy beat]
Dark luminary shine in the night so bright
He started to attract a pair of envious eyes
The villain rose up from behind the jester's cross
He drove him away but didn't know what he had lost
Star and her wand
How could he know Toffee would take 'em for himself?
He confessed to Star’s parents, all full of dread
The King and Queen exchanged a look, and this is what they said
This is what they said, this is what they said:
"We will keep your silence for you
From the citizens of Mewni and the High Commission too
To keep the peace, we will play the game
Royal secret from royal shame
Royal secret from royal shame"
Royal secret – one last to tell
A princess under true love's spell
[upbeat rock beat]
Who is the girl in the mewnian attire?
The princess of the princess's deepest desire
I don't need to show it, I think we all know it
But just to be certain, I'll say it again
Marco Diaz is in love with her best friend!
[quickly] And her name is Star Butterfly.