This is a Layer 3 version of the cloud background seen in some levels in SMW (such as Cheese Bridge Area). It uses few enough colors that very little was lost in the 4bpp -> 2bpp transition; the only thing different about it is that the oval clouds no longer have eyes.
allowiscous' custom tilemap and palette also included.
mod note: as the original status bar will cut fullscreen layer 3 backgrounds off, you may want to use a status bar patch (e.g. Sprite Status Bar)