Weighted clothing are clothing fitted with built-in weights to make them heavier than ordinary clothes.
Weighted clothes are used by several warriors throughout the series. Goku uses weights such as a black undershirt and later a dark blue undershirt and dark blue boots at the end of Dragon Ball in the 23rd World Martial Arts Tournament and during the battle with Raditz. The weaker Z Fighters use weights to train for the arrival of the Saiyans at Kami's Lookout. Finally, Pikkon demonstrated his use of weights, during the Other World Tournament, against Goku.
Weighted clothes suppress a warrior's full power while training. The mass of the weights can be increased to gain more power. Weighted clothes generate similar results as gravity training, but are limited by how little they can increase the user's weight in comparison. Weighted clothes are more versatile though, because they can be used to gain immense power on even low-gravity planets. More importantly, weighted clothes can be used alongside gravity training, for example when Goku trained on King Kai's planet, and when Piccolo trained in the Hyperbolic Time Chamber.
The original use of the weighted clothing is revealed in the battle between Goku and Tien Shinhan during the 23rd World Tournament, where Goku explains that Kami had him use them as part of his training at the lookout. Tien holds all of his weighing clothing, estimating them all adding up to at least 250 pounds (113 kg) (boots, armbands and shirt 50 pounds each). Having shed his burden, Goku then proceeds to "warm up" through a series of whirlwind speed attacks, which provides a pleasant show for the crowd. Despite being the most humorous fight involving weights, it is most certainly not the battle in which the removal of the clothes made a significant difference.
In the battle against Raditz, it was shown that the weighted clothing of Goku and Piccolo made it so that they could only use around 80% of their maximum power. As time goes on, weighted clothes become less significant in battles. Goku stopped wearing weights in his clothes altogether after his training with King Kai in the Other World, due to King Kai removing the weights from Goku's undershirt, boots and wristbands among other modifications to his uniform via Magic Materialization.
The battle which holds the title of "Most obvious difference" is between Piccolo and Frieza's second form. After the assimilation of Nail, he is already fighting evenly with Frieza. Finally, he takes off his weights, becoming strong enough to dominate Frieza in his second form, a feat that no other warrior had done up to this point. This is what pushes Frieza to display his previously unseen 3rd form.
Other occasions were weighted clothing being removed causing a change in the fight include Piccolo's fight with Dr. Gero, where he was easily beaten with the clothes on, but after removing them he completely overwhelmed Gero. Additionally, in Super Namek Piccolo's fight with the Androids, were with weighted clothes he is around the same strength as Android 17, and after removing them is able to fight for a long period against the Android, despite him having limitless stamina. When Pikkon wears his weighted clothing during his battle with Goku, he is somewhat superior to Goku's base form, but after removing it, he is superior to Goku's Super Saiyan form.
Goku uses weighted training gear (both wrist and ankle weights) while training in the Other World for the 25th World Tournament on Earth. South Kai changes his weights from 2 tons to 10 tons on each leg and foot, totaling 40 tons altogether, and Goku turns Super Saiyan to handle this increased weight.
During Goku and Vegeta's training with Whis, Whis at one point forced them to fight while wearing extremely heavy training clothes that made it hard for them to even move, despite being Saiyans beyond God.
Video game appearances
Called Heavy Karate Outfit in Dragon Ball Z: Attack of the Saiyans, weighted clothing are a capsule item which increases the Z Fighters' EXP as they walk. Heavy Karate Outfit is obtained by wishing for a unique item using Mr. Popo's Dragon Ball set.
Weighted clothing are incorporated in Dragon Ball Z: Buu's Fury in the form of armbands and boots. In keeping with their use in the manga/anime, wearing them slows down the character, but increases the experience obtained by defeating the enemies. The 1 Ton Boots and 1 Ton Armband can be found early in Other World, while heavier armbands and boots will sometimes be dropped by an enemy. Though the heaviest ones (Kiloton Armbands and Kiloton Boots) can be bought on the planet of the Kais. The heavier the armbands/boots, the higher level the characters have to be at to equip them.