He made his debut in Super Mario RPG, which remains to this very day,Super Mario Wiki said:Boshi is a Blue Yoshi with an attitude, and the rival of Yoshi. Boshi is a loner and wears sunglasses and a spiked collar around his neck. 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.