Yoichi Kotabe and Shigehisa Nakaue
Everybody in the internet keeps attributing those 2d, old style Mario illustration to Kotabe, who been retired from nintendo for more than 10 years now, when in fact, they are drawn by designer Shigehisa Nakaue, this misinformation keeps spreading again and again.
Source :
https://nadgame.blogspot.com.br/2014/01/3d.html
https://ja.wikipedia.org/wiki/%E4%B8%AD%E6%A4%8D%E8%8C%82%E4%B9%85
http://www.musee-nintendo.com/musee-nintendo/goodies-planche-de-dedicaces/