Dragon Ball Z is full of power-ups. While Dragon Ball fights were often resolved with super-secret techniques, superior martial arts or technical skill, Dragon Ball Z required its heroes to massively increase their powers to even bruise some of their super-powered adversaries. However, when analyzing what sort of power-ups best served Goku and friends, two particular transformations stand out: the Kaio-Ken and Super Saiyan transformations.
However, when looking at the two techniques over the years, it becomes clear that both transformations are incredibly useful at their given points in the series. But which one is the superior technique? Let's analyze their strengths and weaknesses as well as when they turned the tide in combat.
Vital Moments
The Kaio-Ken technique proved invaluable throughout the Saiyan Saga and Frieza Saga, while every fight that followed required the Super Saiyan transformation. The Kaio-Ken technique allowed Goku to beat down Nappa and stand toe-to-toe with Vegeta, the Ginyu Force and, ultimately, Frieza. However, the Super Saiyan transformation is what turned the tide in every battle to follow.
That said, the Super Saiyan transformation also proved a counterproductive technique as well as a practical one. Trunks' Ultra Super Saiyan form increased his strength but slowed him down so much he couldn't land a blow on Cell. Goku's Super Saiyan 3 form, while mighty, burned too much energy and ultimately failed to turn the tide against Majin Buu. Super Saiyan 3 and 4 greatly reduced the time Fused Heroes like Gotenks and Gogeta could remain fused. While the Super Saiyan transformations offered heroes a chance to win, they also ended up harming the heroes just as often.
Undeniably, the Kaio-Ken also turned the tide in battle when it looked like everyone was going to die. But so did the Super Saiyan technique. While Goku would never have made it to the Frieza Saga where he first transformed into a Super Saiyan without the Kaio-Ken, every saga in Dragon Ball Z required some power-ups or training, so it could be argued that both techniques proved equally vital to advancing the plot.
During Dragon Ball Super, however, the Kaio-Ken made a return as an added boost to the Super Saiyan Blue form. This dramatic boost, combining the two techniques, put an incredible strain on the combatants, but ultimately made Goku's on par with adversaries like Hit, Kefla and Jiren.
Power-Ups and Strain
Both abilities offer incredible potential to their respective heroes. Both the Kaio-Ken and Super Saiyan transformations multiply the user's powers by a significant quantity. The Super Saiyan transformations -- be it Super Saiyan 1, 2, 3, 4, God or Blue -- multiplies the combatant's power by a massive amount. Transformation requires the user to undergo some extreme emotion, usually anger or sorrow, but once triggered, the user can maintain this form for a great deal of time. In fact, Goku and Gohan train by maintaining the Super Saiyan form for long periods of time, managing to control the energy naturally.
On the other hand, the Kaio-Ken technique can be taught like any other. It puts the user under incredible strain, increased by how much they're multiplying their energy. In Dragon Ball Super, even after years of training, Kaio-Ken still makes Goku practically convulse and renders him vulnerable after use.
To better demonstrate the different strain both techniques put on the user, consider the fight with Frieza. Goku barely manages to use a Kaio-Ken x20 for more than a few seconds, but once Goku transforms into a Super Saiyan, he maintains the form for the rest of the fight. Super Saiyan is easier to maintain, which makes it more practical.
Ultimately, the Super Saiyan transformation has proven to be a far more important technique due to the increase in power it offers and how Saiyans can transform into a Super Saiyan without running the risk of their bodies breaking under the strain of the technique. The Kaio-Ken just can't stack up.
