Nintendo announced during their latest 3DS Direct that Super Mario Maker 3DS is coming to handhelds everywhere. the retail copy of the game will come with one hundred new levels designed by Nintendo, and will support most, but not all, of the levels built for the Wii U original.
As far as playing the game, the normal 100 Mario Challenge mode will be available, grabbing levels from the online archive. The game does lose some functionality on the way to handheld, as the Mystery Mushroom and amiibo functionality will be exclusive to the Wii U original.
As far as creation is concerned, all the tools from the Wii U game will be usable in the 3DS version of the game. Once you finish your levels, they'll be limited to sharing locally or via Streetpass, as there will be no online uploading. However, if you get together with friends, you can share unfinished levels locally to create levels together.
Super Mario Maker 3DS will hit stores this year, on December 2nd.