World 8-Tower (New Super Mario Bros.)
From the Super Mario Wiki, the Mario encyclopedia
In the first part of the level, the player must jump across a spiked gap onto a moving platform. The player must then make their way upwards using more moving platforms, while avoiding spiked walls and Dry Bones. Eventually the player will come across a large moving platform; they must quickly Wall Jump onto the platform or else they will be crushed. Past this is a very narrow passageway with a ceiling covered in spikes; while Small Mario and Mini Mario can safely walk through it, powered-up versions must duck and let a moving platform push them through the passageway in order to avoid taking damage. Past the passageway, the player finds more moving platforms, along with a pair of Spike Tops guarding a pathway. The midway point is found immediately after this area.
The last part of the level contains more moving platforms (some of which will try to crush the player), spikes, and Dry Bones. To reach the boss door, the player must use a trampoline to carefully time a jump onto a moving platform. Above the platform lies the boss door, guarded by two Dry Bones, and a Flying ? Block.
Beyond the boss door lurks Bowser Jr. in his penultimate solo fight. He is fought on stable ground surrounded by Burners and moving platforms, and cannot be jumped on; he will only take damage from shells and fireballs from Fire Mario. After being hit with three shells or ten fireballs, he will be defeated, and World 8-3 will become accessible.