For that, it sounds like you want to use Layer 2
. The SNES features up to 4 layers (or rather, only 3 most of the time) which you can put tiles on, and then scroll indespendantly of each other. SMW uses Layer 1 as an object
layer (where you put ledges and whatnot), which you edit with
. Layer 2 is generally a background
layer (where it's just a flat tilemap), which you edit with
However, you can also switch Layer 2 to be another object layer like Layer 1. To do this, open the level header settings
, and switch the level mode
(the dropdown at the top) to either setting 02 (for a horizontal Layer 2 level) or 08 (for a vertical one). You'll notice the text below the box will indicate that fact. When you click okay after doing this, Lunar Magic will give you a couple warnings about how your level will be affected by this; click okay to both. As a result, you'll probably notice your background disappears. That's because Layer 2 is now an object layer, editable with
the same way Layer 1 is.
So, how does this then help you with your scrolling platforms question? Well, go into sprite-editing mode and open the sprite selector, then switch the dropdown to "special commands and generators". Scroll down a bit to sprite E9 and below, and you'll notice there's a bunch of generators that affect Layer 2. You can use these to control Layer 2 in your level and make it scroll or smash the ground (see Wendy's Castle, level 1A, for an example of the smash). Just place that sprite at the top of the screen you want the scrolling to start, change any settings noted in the sprite's description (most commonly, set the Layer 2 vertical scroll rate under
to 'none'), and you should be good to go.
Also, worth noting that if you still want a background with Layer 2, you'd want to take the next step down and add Layer 3
to the level. Layer 3 is a bit wonkier than Layer 1/2, but there's a basic guide on it here
Professional frame-by-frame time wizard.