From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Gigantification caused the user to grow to enormous proportions, as they reached a size of nearly ten times their original size and increased their power by an unspecified multiple. It was quite likely that any Namekian was capable of initiating this transformation provided that they knew how, as both Slugg and Piccolo were capable of transforming in this way. Piccolo transformed like this once in the manga and twice in the anime. He first transformed in his fight against Son Goku during the Piccolo Jr. Saga. He then transformed even bigger, but found this form to be ultimately ineffective against Goku (this was in both the anime and the manga).
Dragon Ball Z
Piccolo transformed a second time (only in the anime) to counter Super Garlic Jr. (The Garlic Jr. Saga was an anime-only filler saga and Piccolo found the technique to be very effective against Garlic Jr. because, despite his greatly increased size and strength, he did not sacrifice speed for the increased power and remained just as fast as he was before he transformed. In the anime, he even went on to tell Garlic Jr. that "You can't sacrifice speed for power, not against me.") This was not the case for Garlic Jr., whose enlargement came at the cost of speed. Piccolo Daimao was abnormally tall for a Namekian and could also increase his size somewhat, as displayed just before he unleashed his destructive wave on Goku, though it was never confirmed if this was the same technique.
It is named Great Namek in Dragon Ball Online.
It is named Giant Body Jutsu in the Dragon Ball Collectible Card Game.
- Chō-kyoshin Jutsu – The Chō-kyoshin Jutsu (超巨身術, Chō-kyoshinjutsu; Literally meaning "Ultra Large Body Art") is a technique where the user concentrates the nerves throughout their entire body, invigorating their body's cells. As they grow gigantic, they let out a scream of pain due to the excessive additions to their body. This technique's strong point is that the user's speed does not change despite them becoming gigantic. Piccolo used this in the finals of the 23rd Tenkaichi Tournament after his inability to win made him lose his head.