Ok so the music is called Drops of H2O, don't know what artist. And I never used the username block (scratch, you idiot). Go ahead and use different costumes for the sake of... yeah, making it your own. I had been most successful with sizes of 360-370 pixels squared. You can still use different sizes, but results may not be as good.
Artwork is also found on my YouTube channel: https://www.youtube.com/channel/UCyAaNY930jtbL305MojK8iA.
