The relationship between Goku and Vegeta in Dragon Ball canon is one of perpetual challenges and comparisons, as both Saiyans make each other stronger with every increase to their own power level–however, there is one challenge Vegeta made to Goku that has remained unanswered, and it is something fans have been begging to see for decades.
From the moment they met, Goku and Vegeta have been the greatest of rivals. In the early days of DBZ, Vegeta invaded Earth with the intention of conquering the planet, and Goku did everything in his power to stop him. After Vegeta was defeated, Goku allowed him to live as he knew the two of them were not done making each other stronger–and he was right on the money. Since that moment, Goku and Vegeta have each strived to be the strongest warrior in the cosmos, and in doing so, made each other stronger as well. From the initial Super Saiyan transformation in Dragon Ball Z to Dragon Ball Super’s Super Saiyan God and beyond, Goku and Vegeta have been neck and neck in terms of power scaling–which is actually what leads to Vegeta delivering this challenge to Goku in the first place.
Vegeta Challenged Goku to Unlock Super Saiyan 5 (Just Like the Fans Did)
In Dragon Ball GT episode 55 (written by Atsushi Maekawa, directed by Osamu Kasai, produced by Toei Animation), Goku and Pan are traveling the world, defeating the Shadow Dragons before they decimate the planet. Meanwhile, Vegeta is at his house, thinking back on how Goku has always surpassed him before he eventually catches up with his Saiyan rival. Rather than letting this thought anger him (as many would assume it would), Vegeta was surprisingly calm about everything and decided that he was done comparing himself to Goku, and that his worth would be measured by his own accomplishments alone, and that will be enough. And then, Bulma tells him how she can help him unlock Super Saiyan 4 and that previous sentiment goes right out the window. With the knowledge that the most powerful Super Saiyan transformation to date is within his grasp, Vegeta proclaims that no matter how powerful Kakarot gets, he’ll be right behind him–even if Goku unlocks Super Saiyan 5.
While Super Saiyan 5 isn’t a canonical transformation within Dragon Ball (and Vegeta only said it as a facetious, broad statement covering any future transformations), the fact that Vegeta said it at all is incredibly exciting, especially given the buzz surrounding Super Saiyan 5 within the Dragon Ball fandom. Back in the early 2000s, there was a rumor floating around about a sequel anime series to Dragon Ball GT called Dragon Ball AF, and this ‘new series’ was going to feature the all-new Saiyan transformation: Super Saiyan 5. There was even iconic fan art of Super Saiyan 5 that was paraded around online as official Dragon Ball AF concept art, but in the end, it all ended up being a complete fabrication.
In a way, Vegeta’s challenge for Goku to unlock Super Saiyan 5 (whether literal or not) is something that the fandom doubled-down on. Everyone in the early 2000s wanted to see Super Saiyan 5 in action, and with it being officially named in Dragon Ball canon during this episode of GT, there is a very real possibility that the future of the franchise will include this long-awaited transformation–at which point, Goku could finally answer Vegeta’s greatest Dragon Ball challenge.