In Super Mario World, Mode 7 boss battles appear to have backgrounds even though this should be, on a technical level, literally impossible. This is done by using sprites to "fake" a simplistic background layer. Details in image.
@MarioBrothBlog Clever use of changing BG modes mid-frame
@MarioBrothBlog SMW, where the background is made of sprites and the boss is made of background
@MarioBrothBlog Levels with moving layers did something very similar, albeit with simple Layer 3 Backgrounds. Layer 3 backgrounds are limited in the colors they can use, and can't touch the status bar, as that also utilizes Layer 3.
@MarioBrothBlog So Morton is the background and the background is a sprite, wow, old-school games developers were so inventive.
@MarioBrothBlog That's mindblowing. Literally reverse of how it normally works, boss is background and background is sprites.
@MarioBrothBlog never should have smoked that shit, now i'm in the morton zone
@MarioBrothBlog Hey, it’s something I actually know a bit about I think it was executed A LOT better with Hookbill in YI, with a seamless transition and the background appearing to be the mountaintops having become shrouded in fog