You have to help Mario cope with falling Goombas, Bloopers, Boo Buddies, and Piranha Plants. As they fall, catch them on trays. Switch and shuffle them to save the day. Stack two of a kind and they both disappear. Or capture a whole bunch between two eggshell halves. A different kind of Yoshi will appear depending on how many enemies are between the eggshell halves. There is a password feature to save your progress.