If you haven't seen it yet, here's the theme they used for the Once & Always special:

[youtube]https://youtu.be/VGEZgXISMwc[/youtube]

And here's a fan-made version:

[youtube]https://youtu.be/Qgh_CRy12Ww[/youtube]

And here's their morphs:

[youtube]https://youtu.be/ZXIiqFQdifM[/youtube]