Apparently Wario Was Mario's Childhood Friend and Bowser "Could Not Stand the Idea of Happy Fungi" and more info about each characters history

[forethought14]

Mario probably did something bad to Wario.

I still wonder about the legitimacy of these "ideas", it's never explicitly stated if they originated at Nintendo Co. Ltd, or just off the minds of the NoA people. In other words, let mii sii reciipts pliize! (reciipts that are direct from the creators, not some wild fandom created by NoA)