Big G is the big, strong, and quick-tempered local bully. He also frequently steals other children's toys and books under the pretext of "borrowing" them, unless the toy is damaged. However, Big G does not hesitate to help his friends when they are in real trouble; throughout the series, particularly the films, he is often the one who voices the most concern and refuses to look away when there is a problem, an opposite of Sneech's cowardice. While he is described by others as daunting and intimidating, he is very sensitive and prone to crying when something touching happens. Big G also has a soft spot for his younger sister, Little G, and usually tries to prevent her from trouble, even if she can perfectly handle her situation.

He is known for his boastful confidence in his horrible singing voice, though he considers himself a great singer. His singing voice is so horrible that in a story in which Noby and Doraemon try to mute it in a silent world, his writings of the song lyrics in a board end up having the same effect as when they hear them, and in some films, his singing is enhanced to become an effective weapon comparable to an explosion. In some episodes when his voice is recorded and he hears it, he instantly denies it being his voice and threatens to beat up the person who sung his songs in a very bad way. Several of the stories revolve around Noby and his friends' efforts to avoid Big G's concerts. Big G is also confident in cooking, but just like his singing, his hand-made food can be a nightmare for other people very easily.