Great Grapy is one of the Boss Pirates, the leaders of the Tabemon Monsters from the video-game "The Munchables".
Great Grapy takes his name from the fact that he resembles an anthropomorphic cluster of grapes and is easily enraged, much like the other Boss Pirates.
He threatens to crush the hero and its companions for daring to invoke his wrath and attacks via spitting out a torrent of explosive grapes at the hero.
The only way to harm the giant alien was to fire the grapes back at him, causing him to fall apart and thus be easily devoured.