Thanks to the generous work of AGenericFoxMain, who you may know for his Project M stage ports, animated collisions are now working. However, the UFO was unable to disappear without everyone standing on it instantly dying, so the animation has been modified. I will add the download to animated Fourside shortly. Keep in mind I have not implement 8-player compatibility yet. "Yet" is the key word.
Since animated collisions are the only thing not working for me, I decided to release the static version of this stage over Onett Omega for beta. You're welcome!