A Goomba named Zachary is tired of working for Bowser, and decides to leave the castle with his friends Wendy and Perry. A mushroom falls on Zachary's head, giving him his nickname, Mushroomba. Once Bowser notices that Zachary and his friends are missing, he sends the Koopa Troop out to find them.
Mushroomba (real name Zachary) believes there is no point in trying to defeat Mario, so he ran away from the castle and decided to go on an adventure.
Wendy is a Waddlewing who is very daring and adventurous. She will do almost anything that Mushroomba says.
Perry is a Piranha Plant with extremely high IQ. He is a vegetarian, so he did not like eating living things. This made him decide to go on an adventure with Mushroomba.