*Dr Ray Stantz:
Ray Stantz was responsible for the selection of the Stay-Puft Marshmallow man as Gozer's incarnation on this plane of existence. His fond childhood memories of the mascot led him to believe it could never possibly harm them.
Stay-Puft Marshmallow Man (Happy):
Even after causing millions in property damage, the Stay Puft Marshmallow Man seemingly recovered from his possession by Gozer and even went on to become an ally to the Ghostbusters team. As Peter Venkman put it, he is "all better now." *Source: Back of package