Over on Miiverse, Sakurai has revealed a brand new stage for Super Smash Bros.: Mushroom Kingdom U! Based on New Super Mario Bros. U, the stage is fairly simple, featuring a wide low platform and several smaller ones above, and even some platforms that look to be Stretch Blocks. Stretch Blocks have appeared in multiple Mario entries. They extend outwards and retract every few seconds, requiring some timed jumps to overcome.
But that's not all. Like the Pokémon Stadium stages from previous Smash Bros. games, Mushroom Kingdom U periodically changes. Every so often, Bowser's toady Kamek will pop a spell that transforms the stage. Apart from the background changing to match another section of the source game, the stage loses its upper platforms. In their place are water spouts that serve the same purpose, but probably only last a few seconds each, and there's even a spiked fish obstacle.