I was curious if Earthbound style battle backgrounds were possible in C3 since we have no control over its rendering and it doesn't really have webGL effects to do this. Apparently you can! And with no webGL effects required. They were originally called "video drugs".
Sample of what this does. I used Windows 95 wallpapers since this is just an example.
All you need is tiled backgrounds.
Comments on what everything does are in the file. It doesn't require anything special and you can just modify my example if you want.
Example project file: