-The ability to create a simple scrolling stage. Upon building a stage, you will be prompted to select whether you want to build a 'Standard Stage' or a 'Scrolling Stage'. If you choose to make a scrolling stage, you choose which direction it scrolls (upwards or to the right). The editor will look slightly different for a scrolling stage - the place where you build will be a long strip (horizontal or vertical depending on which direction you chose for it to scroll). When playing the stage, it will loop through the entire strip (like Mushroomy Kingdom). You can tweak the scrolling speed too.
-The ability to build in three 'planes'. You could place stage parts into any of the three planes, to create depth in your stages. The front and back layers are simply cosmetic - the players fight on the middle plane only. The applications for this are endless.
-Different textures for blocks regardless of what background you are using. You would be able to use grass, stone, sand, snow, ice, metal, etc.
-More than three backgrounds - I'm thinking around eight (including clouds, space, ocean, volcanic, etc), plus a few unlockable Nintendo-themed backgrounds.
-More hazards such as water (and lava), see-saws, pulleys, and some simple button/gate mechanisms.
-More decorations such as plants and rocks.
-Unlockble Nintendo-themed decorations and hazards, such as Blocks and Pipes from Super Mario.
-The ability to select up to four songs per stage - how often they play can be tweaked similar to My Music.
The stage builder would primarily use the GamePad. Stages could be shared on Miiverse.