In Dragon Ball Super, Goku and Vegeta are still working to master their respective god-like powers, from Goku’s Ultra Instinct to Vegeta’s power of destruction. Even before the Saiyans knew such power was even attainable, they still tangled with beings wielding power beyond their understanding, including the God of Destruction himself, Lord Beerus. At the beginning of Dragon Ball Super, both Goku and Vegeta fought Beerus in an attempt to save their world. While the outcome of their experience with Beerus made both Saiyans reach new levels of power, most notably Goku who was the first to break through the barrier of Super Saiyan God, they were no match for Beerus. Since their first encounter, however, their power levels have grown exponentially, and if they were to fuse together, they could conceivably defeat the God of Destruction

After meeting Lord Beerus as the God of Destruction threatened to destroy the Earth in Dragon Ball Super: God of Destruction Beerus Saga by Akira Toriyama, Goku and Vegeta begin training with the being that is responsible for training Beerus himself, the angel Whis. Initially, Goku and Vegeta train with Whis together, both working towards achieving the angel’s greatest move, Autonomous Ultra Instinct. After their powers are put to the ultimate test while battling some of the most powerful fighters in the multiverse, it becomes clear that Goku and Vegeta should focus more on their respective strengths rather than work to achieve the same goal. 

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To that end, Goku achieves the coveted Ultra Instinct while fighting Jiren in the Tournament of Power and ends up being the very thing that weakens Jiren enough for Universe Seven to claim victory. After the tournament, Vegeta doesn’t go back to training with Whis but calls Beerus his new master as the god teaches the Saiyan the techniques of destruction. Goku studies with Whis to learn the powers of the angels while Vegeta trains with Beerus to learn those of Gods of Destruction, and eventually, their training pays off. Goku is able to use Ultra Instinct more sustainably while Vegeta unlocks the power of destruction. 

When Lord Beerus fought Goku right after Goku unlocked the power of Super Saiyan God, Whis revealed afterward that Beerus was using seventy percent of his power, something he hadn’t had to do in some time. Back then, Goku couldn’t even reach Super Saiyan Blue and was just beginning to learn Super Saiyan God, and Vegeta was nowhere close to either form. Now, Goku and Vegeta have reached power levels of the Gods of Destructions and of the Angels respectively, so if Beerus had to use seventy percent of his power to fight the weakest version of Super Saiyan God Goku, then it is possible that the combination of Ultra Instinct Goku and God of Destruction Vegeta could defeat Lord Beerus. 

While Beerus has never fought the fusion of Goku and Vegeta known as Vegito in his strongest form, the Dragon Ball Super manga confirmed that the previously stated theory is more than plausible. At one point in the series, Vegito’s power level does surpass that of Lord Beerus, though unfortunately just because the power of a Saiyan can surpass another’s doesn’t mean they can beat them in a fight. Saiyans’ incredibly high power levels can drain their energy as fast as it gives them the required strength to defeat their foes. While Vegito may have surpassed Beerus at one point, fans have still never seen the god’s full power against the stamina of Vegito. Only Goku and Vegeta’s fusion can surpass Dragon Ball’s God of Destruction, but whether or not they could actually defeat him has yet to be seen.

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