New Super Mario Bros.: 8-Fort

This Fort has more platforming using sliding stone slabs while avoiding spikes. The first Star Coin is on the left side. Duck and let the stone slab push you under a gap. Go up and avoid the Spike Tops. The second Star Coin is on the left side. Keep climbing and you'll reach the midpoint and, eventually, the boss door. Before you go through the boss door, hit the flying item block, preferably in the middle of the room. Jump on it and hit the invisible block above, then jump off that block to reach the third Star Coin. Through the boss door, we find Bowser Jr. with his mask on, on moving stone platforms over jet engines. Use fireballs or the shell he throws for victory. He takes off with Peach to the castle.