World 2-Castle (New Super Mario Bros. 2)
From the Super Mario Wiki
World 2-Castle is the castle of World 2 in New Super Mario Bros. 2. The level is spent nearly entirely on a platform that only moves if the player is stepping on it. Fireballs attempt to lurch out and hurt the player in this level.
The player starts out on a flat surface, where the moving platform is docked. After jumping on the moving platform, a few Buzzy Beetles are encountered, moving around on Brick Block structures. When the player approaches the structures, they fold out, dropping the Buzzy Beetles onto the platform. Soon after, Thwomps appear. The player can bait these Thwomps into crashing into lava, destroying them. Shortly after, the Checkpoint Flag appears along with two ? Blocks, one of which has a Super Leaf inside. Another platform is docked here. The platform quickly approaches a quad of fireballs and the second Star Coin rotating above. The level's Red Ring is located directly after this, floating above a set of Brick Block structures. Shortly after, a dual set of fireballs and a red pipe appear on-screen. After a few more sets of fireballs, the boss door appears.
The boss is Iggy Koopa, riding around in his Chain Chomp carriage. The battle plays extremely similar to his Castle battle in New Super Mario Bros. Wii. The player must stomp him on the head three times to defeat him.