The Super Giant-Form is considerably larger than the previous Giant transformation. When Piccolo used this against Goku, the World Tournament announcer said he was as big as a volcano (or mountain in the manga). However, Goku takes advantage of Piccolo's gargantuan size in order to retrieve Kami, causing him to realize the flaws of the form and thus return to his base form.
Lord Slug also used this form against Goku, with more success. He was able to grab Goku and almost crush him, but Piccolo ordered Gohan to whistle. Namekians are sensitive to whistling; it normally causes them discomfort, but with Slug's enlarged ear drums, the whistling caused him immense pain.
Main article: Dark Evolution
In the Dark Empire Saga of Dragon Ball Heroes, after merging with the Six-Star Dark Dragon Ball, Slug is forced to undergo a dark evolution due to Towa. Lord Slug takes on the Dark Giant version of the Super Giant form, gaining a dark energy from his head and back, and merging with the Earth itself.