Mega Goomba (boss)

Mega Goomba is the boss of World 4 in New Super Mario Bros..

Before the battle, a seemingly regular Goomba transforms into this Mega Goomba. Mario must defeat this boss to aquire the key that provides access to World 5.

To defeat Mega Goomba, Mario can activate a switch, causing two platforms to appear. When Mario stands on the platform, it will elevate in the air. From there, Mario can either Wall Jump, Jump, or Ground Pound directly on top of the Mega Goomba. For the attack to be successful, Mario must Ground Pound the Goomba (unless he is Mega Mario or Shell Mario). Mario can also go off to the side, simply wall jump, then ground pound on the Mega Goomba.

Once Mario hits the Mega Goomba three times, the Goomba will be defeated, and Mario can get the key to World 5.

Interestingly, the Mega Goomba is the only boss in the game (other than Petey Piranha) that can be defeated using one jump with a power-up other than the Mega Mushroom. In order to do this, Shell Mario needs to go to the wall then wait for Mega Goomba to stop at the wall. Once Mega Goomba hits the wall, Shell Mario needs to jump while in the crouching position. Normally, when Shell Mario hits the Mega Goomba, Shell Mario will go in the opposite direction. Since hitting the wall lets Shell Mario to go towards the other wall when he hits Mega Goomba the first time, Shell Mario will hit the Mega Goomba 2 more times (according to the game) due to the fact that Mega Goomba has a few invincibility frames.

Trivia

 * This Goomba originated in the very first previews of New Super Mario Bros. or as it was called back then, Super Mario Bros. DS in which it was a normal level enemy Goomba until it was caught in contact with a Mega Mushroom which made it the same size as it was in the current game. This new and innovative feature was taken out for unknown reasons, possibly due to the game being extremely hard if certain enemies turned mega.
 * When the Mega Goomba grows, it makes a sound similar to Mario changing into Mega Mario, only it is somewhat more evil-sounding.