During today’s Nintendo Direct, the Big N announced some brand new updates that are coming to Super Mario Maker. When creating your challenging levels, you can now shake a P switch or coin and turn it into a key, or shake a door and change it into a key door. With this latest update, you can create levels where you cannot advance without a key, which is good for those players who want to include mandatory boss battles. If you want your level to be more challenging, you can now turn Thwomps into the skewers from Super Mario World as well.
In addition to the new items,
Super Mario Maker will also be getting a Super Expert Mode to the 100 Mario Challenge. This new update will be available for download on March 9th.
Source: Nintendo Direct