Details
Golden Plains is a rather inocuous level based upon the recent 2D platformer, New Super Mario Bros. 2 which had a focus on coin based mechanics. As such, this stage fully continues this with a gimmick that isn't possible on home consoles.
Dotted around the stage are coins which will continually respawn. If you collect 100 coins, then you will act as if you picked up the Gold Flower power up from the original game. When this happens, for a short time your character is golden and has increased attack power and flinch resistence.
After some time battling on the stage, you will discover that the stage will move to the left or the right briefly. This provides new areas to brawl within. On odd occasions, a P Switch will appear and, if hit, will bring lots of blue coins. In addition to that, you may find a red coin ring. If you get that ring and collect all 8 coins, you will receive a boost