Bowser

Bowser is a character who appears in several stories of the series. He is also usually involved in a laughing joke along with Random Chinese Guy and sometimes the Fourth Wall. He was the main villain in Puffle (Launcher) Lawn Chair.

(Not So) Elite Penguin Force
In (Not So) Elite Penguin Force, Bowser appears a few times where he does his laughing joke. He later appears at the end in Castle Bleck, where he is tossed into a black hole.

Puffle Launcher Lawn Chair
In Puffle Launcher Lawn Chair, Bowser is the main villain, although it is not revealed until Chapter 3 in an intermission - however, The Party does not learn about it until much later. The Party then reaches his castle and they fight him in space. It is revealed that he stole Twee's wand, the Star Rod, and becomes invincible. However, Fawful shows up and defeats him.

The Wacky Awesome Super Duper Nothing Show
In The Wacky Awesome Super Duper Nothing Show, he first appears in Hamburgerz where he creates a machine that will destroy the Mushroom Kingdom. However, Rocka after being tossed into a pipe by Chill and Jonnia, comes out of a pipe above the machine and destroys it, falling into the lava pits. Bowser proceeds to cry.

Trivia

 * It is unknown how he survived being tossed into the black hole at the end of (Not So) Elite Penguin Force, as he reappears in Puffle Launcher Lawn Chair.