Make sure it is a remix. Your entry must relate with Yoshi. It could be: Mario riding Yoshi A costume for Yoshi in Mario Kart World and/or Mario Kart Tour. An enemy from a Yoshi game. A setting based on a level from a Yoshi Game. Now remember, these are just some examples! You could draw it digitally or on paper. You can use a reference image too. Don't steal anybody's art.
Nintendo!
