Koopa the Devastator

Koopa the Devastator is a secret boss in Mario Forever. The boss is Bowser but is slightly faster and he shoots faster. After completeing, the player earns 30 1-ups. If the player dies, they get sent back to world 1-4. In the boss fight, the Final Boss music from Yoshi's Island will be played. This secret boss can be only accessed to once per game, as the invisible blocks are no longer available if the player dies once. Usually, because of the blocks' heights, it is hard to reach any of those, however, if the player uses Lui Power up to cheese out this secret boss' access.

Location
The boss is located in world 2-1, in the floating pipe. To get there, there are 2 invisible blocks, 1 having a coin and the second having a Jumping Lui. The boss room looks like a normal Bowser fight bridge.