Zmbuh was the second Bubuh made. He was purple, and therefore given to Tonky Wonky. Tonky Wonky immediately freaked out because of Zmbuh's nasty smile, red eyes, and all around spoopyness, so he built a potion gun and shot one at Zmbuh. Zmbuh survived, and didn't even show any scars. Doopsee saw something in him, and proclaimed that Zmbuh shall be the leader of the Bubuhz. Umbuh didn't like this, though, and said that Humbah was the leader of the Boohbah, so SHE should be the leader of the Bubuhz. She pulled a magnum out, and said that "if you survive, you'll be the leader!" before snickering, because she had hidden a rocket in the magnum.
He was declared leader!!!1!
He is actually very kind, and wants to play with you. But look at him. You wouldn't care what he wants. You'd run away to your mommy thinking that he wants to kill you. And you wouldn't be wrong. His favorite game is "Punchies" where one guy tries to punch the other, and the other tries to run away, and when the runner gets punched, HE becomes the puncher. Zmbuh likes to be the puncher though, and when he punches you, you will DIE. So don't play with him. Run to your mommy instead. Yeah. Who cares if you look like a wuss? You're not dead.
Zmbuh shouldn't exist. No, seriously. Look at that thing. LOOK AT IT.