Do you understand, in theory, how you would even do something like that? You would either need to animate the CHR (which requires a mapper conversion or a conversion to CHR RAM) or add new tiles (good luck, there's no free space in the CHR ROM) and animate the nametable (good luck keeping track of what needs to be animated). It sounds like a simple modification, but unless I'm overlooking an easier option, SMB lacks the necessary features out of the box and as I understand it, there's very space in the ROM to add new data/code/GFX without expanding the ROM and using a mapper.