Rich Plumber is a episode from the 2nd season, in which Mario helps a rich guy on becoming the richest one there is, But Mario must steal money from the richest person in mushroom kingdoom. the rich guy now becomes the richest person there is, and give half of his money to Mario. Mario, being rich, will now abuse of his friends, like:
Kicking them out of the castle, Claiming the castle from Peach, and other things.
This is the only episode that Mario becomes evil, If not in SMG4's videos.