Wario

Wario is Mario's little known brother. Bowser tried to push him into a volcano after they had a battle, but he ended up being caught in a cloud and flung far away. Bowser was left with his jaw open.

Background
Some say he was created by Luigi to stop Mario's moaning, and some say he is banned from eating curry since he tends to blow up randomly a couple weeks after eating some, creating a disturbance.

All we all know, he is called Wario. For no reason indeed. Philosophers say it was because Luigi liked that name.

Involvement
He is a minor character though he has his own boss fight in which you need to tickle his funny bone to defeat him! You must touch his funny bone while avoiding getting caught in Curry Explosions. After you destroy him, he explodes one more time which finally gets you into a boss battle with Mario.

Strategy
Tickle his funny bone. . . he will explode for the last time, or run to a volcano and explode there.