Longtime Dragon Ball Z fans were pleasantly surprised to see the kaio-ken return as a powerful multiplier of Goku's Super Saiyan Blue transformation during his first bout against Hit.  However, that made us at Anime Mojo wonder about the many other techniques Goku and others have employed over the years to raise their power levels.  As any DBZ fan knows, Goku always finds himself in a seemingly insurmountable position, only to reach new heights of power and defeat his foe. 

Since anime fans first met Goku at the age of 12 at the start of Dragon Ball to his encounter with Jiren in Dragon Ball Super at the age of 48 (though physically, he's 40 as he spent several years in the afterlife after exploding with Cell and didn't age), Akira Toriyama has employed  a number of techniques and power-ups to explain how Goku manages to snatch victory from the jaws of defeat, time after time.  Let's revisit some of those ideas and examine whether they're still viable in the current, insane levels of DBS.  After all, people like Tien, Yamcha, Krillin and even Picollo need all the help they can get to stay current with the limitless saiyans.

Weighted Clothing

There's many areas to explore in Dragon Ball lore - the manga, anime, video game and official trading card games can all offer either additional or slightly different information upon the same subject.  In the case of weighted clothing, this was technique introduce to Goku when he first trained under Master Roshi alongside Krillin.   Roshi would have both boys (and later, Yamcha) wearing 50 and 100-pound turtle shells while training on Roshi's island.  Later, while training with Kami to defeat Picollo, Goku wears what amounts to 250-pounds of weighted clothing.

When Raditz first arrives in Dragon Ball Z, it is revealed via his power-level scouter that the weighted clothing worn by Goku and Picollo surprised about 20% of their true power.  However, once Goku trained with King Kai to learn the kaio-ken technique, he stopped wearing weighted clothing for the remainder of DBZ.  Weighted clothing would return in Dragon Ball Super, as Vegeta and Goku wore heavy training suits provided by Whis, with Vegeta remarking that its effects were greater than those he experienced while training in heavy gravity.  How much these suits weighed is never revealed but in the anime, they slowly sink into the ground after Goku and Vegeta remove them.

Gravity Training

Around the time of the Saiyan Saga and Goku's training on King Kai's planet, emphasis on heavier gravity environments replaced the focus on weighted clothing.  Kai revealed that Planet Vegeta has a gravity that's 10x stronger than the earth's, a reason why the Saiyans are naturally so strong.  Luckily for Goku, King Kai's planet also has 10x the gravity of earth, allowing Goku to quickly raise his power level as he prepared to combat Nappa and Vegeta.  

Just after discovering that Goku had become a Super Saiyan and learning that Goku trained in a spaceship that produced gravity 100x stronger than the earth's while on his way to Namek, Vegeta would be shown training in 300 and even 500x the earth's gravity in an effort to obtain the legendary saiyan transformation.  However, just like weighted clothing, gravity training would also fall to the wayside as transformations became the sole source of substantial power-ups.
 

Zenkai Boost 

While on Planet Namek, Vegeta disclosed that saiyans receive a substantial power boost after surviving near-death experiences.  As a result, he would have Krillin blast him right through the chest and then have Dende use his healing powers to keep him from dying.  This was a desperate gambit to increase Vegeta's power-level to make him a credible threat to Frieza.  Ultimately, it didn't work as Frieza would obliterate Vegeta but the reveal would become a key piece of lore and focal point for the DBZ community.  This reveal would also explain how Goku routinely survived and returned more powerful than before after all of his previous near-death injuries from Vegeta, King Picollo, the Red Ribbon Army, etc.

The effects of Zenkai (which is actually an unofficial name provided by the fandom) were even seen in Cell (who has Saiyan DNA) when he returned in his perfect form after blowing up on King Kai's planet.  It theoretically shouldn't have been possible as Android 18 was no longer absorbed in Cells body at the time.   Half-blood saiyans like Goku and Trunks have also exhibited the effects of Zenkai.

Ultra Divine Water

In Dragon Ball, a pre-teenage Goku trained with the 800-year old Korin to defeat the Red Ribbon Army's, Mercenary Tao.  The goal of Korin's training was for Goku to obtain the Sacred Water, which ultimately proved to just be tap water.  The trick to the power-up lied in the unorthodox tasks and chores Goku had to perform under Korin's direction.  Later, when King Piccolo returned, Korin would reveal that he actually did have a magic, power-boosting water, the Ultra Divine Water. 

Legend stated that the Ultra Divine Water would draw out all of the drinker's latent potential if he or she could survive its poisonous effects.  It is believed that Goku drinking this liquid resulted in a double power boost for the young warrior as he would have received a power-up from both the liquid and zenkai, after withstanding its poison.

Unlock Potential - Babidi, Grand Elder Guru, Old Kai

The would of Dragon Ball is full of ancient, mysterious mystics who all seemed to have the ability to instantly make someone stronger. Essentially, the power-up provides the same kind of boost as the Ultra Divine Water, just without the poisonous after effects.  Grand Elder Guru's powerup of Krillin and Gohan on Namek was crucial to their survival.  

The evil wizard Babidi was shown to be able to give power increases by imbuing them with his magic, as evidenced by Majin Vegeta.  Later, Old Kai would unlock all the latent potential in Gohan in preparation for his fight with Buu.  Gohan's potential was so great that Dragon Ball Z would end with Gohan as the single, strongest non-fused warrior. 

Many years of non-training severaly weaked Gohan at the start of Dragon Ball Super, leaving many in the DB fandom to wonder is a second potential unlock session with Old Kai would return Gohan to his previous height of power.