"In Japan, Boshi's name is Washi (i.e. "Bad Yoshi"), created by combining the word "Yoshi" with the Japanese word for bad, "Warui". As such, Boshi is to Yoshi as Wario is to Mario, or Waluigi is to Luigi."
-MarioWiki
Though he's never interacted with Wario in any game, I've always associated...