While Goku and Vegeta have seemingly been neck-and-neck throughout their respective Dragon Ball careers in terms of strength, there was one point in the franchise where the gap between them was enormous, and it was at this point that only one fighter was nearly identical to Goku when considering power level–and it certainly wasn’t Vegeta.
While Goku was introduced in the first chapter of Dragon Ball, Vegeta didn’t come into the franchise for another roughly two-hundred chapters–but once he did, Dragon Ball was never the same again. Vegeta was a truly vicious villain who loved killing people he viewed as weaker than himself, which, unfortunately, encompassed most of the known universe at that time–including Goku. During their first fight, Vegeta effectively beat Goku one-on-one as it took the combined might of Krillin, Gohan, and Yajirobe to finally beat Vegeta and send him running, but if those other fighters hadn’t intervened, Goku would be dead by Vegeta’s hand. While Vegeta was off to a superior start regarding his endless efforts to be better than Kakarot, it wouldn’t take long for Vegeta to be left in the dust–and by more than one Saiyan, at that.
In Dragon Ball chapter 331 by Akira Toriyama, Trunks is facing off against Mecha Frieza after traveling back to the past with much bigger fish to fry. Since Frieza is nothing more than a minor inconvenience at this point, Trunks makes quick work of Frieza by powering up to Super Saiyan and killing the vile tyrant like it’s nothing. Meanwhile, the other Z Fighters (minus Goku as he was off-world at that point) are making their way to Frieza’s landing site but are still some distance away. When they feel the Super Saiyan ki, however, all of them–including Goku’s own son, Gohan–are convinced that it’s Goku who’s facing off against Frieza just as he did on Planet Namek. Gohan even definitively says, “It’s dad! It’s the same size ki as dad’s when he was on Namek!” proving that, as far as power levels went, there was no difference between Trunks and Goku.
Why Trunks is Truly Goku’s Equal in Dragon Ball
This stage in Dragon Ball canon is probably the weakest Vegeta ever was in relation to Goku. Goku had already unlocked Super Saiyan and was training on an alien world called Yardrat to learn Instant Transmission–a power that later proves to be greater than that of an angel. Meanwhile, Vegeta is seemingly just as powerful as he was when Frieza killed him roughly a year earlier. This left a power vacuum that was immediately filled by Vegeta’s own son, Trunks, as he filled the role of Goku’s rival in strength–though that only inspired Vegeta to reach even higher.
While Vegeta was way weaker than Goku during Trunks’ first visit to the past, Vegeta quickly earned his title as Saiyan Prince in the years that would follow. After Trunks left only to return in three years to battle the villainous Androids, Vegeta trained virtually non-stop for those three years and arguably surpassed Goku upon the Androids’ initial attack. However, despite the fact that Vegeta made up for his shortcoming, there was a brief moment in Dragon Ball history where Vegeta wasn’t even close to rivaling Goku, which left only Trunks as Goku’s true equal.