Who can Goku, from Dragon Ball, beat in the huge cast of My Hero Academia, and who would beat Goku? This is going to get heated, for sure, so rules need to be established. Goku will be able to tap into Super Saiyan 3 (consider this Goku being just before Battle Of Gods), and any characters from My Hero Academia will be able to tap into their strongest possible forms.
For this article, we also need to treat Goku's Saiyan abilities as a Quirk in this hybrid-setting. It's only fair. So, who are six My Hero Academia characters Goku could thoroughly trounce and who are the four that might destroy him?
10 Can Beat: Deku
How does one determine how one shonen main character might do against another? It requires all the information one has at the moment. Based on this, however, things are not looking so great for Izuku Midoriya. Sure, it was awesome to see Deku unleashed One for All Full Cowling at 100% (MHA Chapter 157), but it required the help of Eri, as it taxed Deku's body to the extreme.
A lot about One For All doesn't make a lot of sense, though. Goku's power level at the first rank of Super Saiyan blows Deku's cowling away already granting Goku about 5o times his base power and with no real risk to Goku's body.
9 Can't Beat: Shigaraki
Tomura Shigaraki's Decay Quirk is absurdly powerful. With a single touch, he can crumble just about anything into a pile of dust. His power has grown so great, for example, he can level half a city with the touch of his hand (MHA Chapter 239).
This all requires him to be in melee range, and though Goku could easily keep out of reach, say, with a Kamehameha, the minute the Saiyan slips up, it's all over.
8 Can Beat: Endeavor
Endeavor is the current Number One Hero of My Hero Academia with the retirement of All Might. But don't let the retirement suggest Endeavor isn't powerful enough in his own right. Hellflame, Endeavor's Quirk is the manipulation of fire and is extremely powerful and among the strongest Quirks out there. However, Goku beats Endeavor with raw strength and speed that the flame-bound hero just cannot overcome.
Goku's speed grows with each successive level of Super Saiyan he taps into, so it's all over before Endeavor can singe a single fiber of Goku's Gi.
7 Can't Beat: Hitoshi Shinso
This one depends on the right circumstances, but if done right, Goku is no match for this student's Quirk. Hitoshi Shinso, from UA High School's Class 1-C, has a Brainwashing Quirk. This Quirk allows him to exert control over anyone who verbally responds to him.
Goku is just dumb enough to respond. To make it worse, Hitoshi's artificial vocal cords allow him to mimic the voices of others (MHA Chapter 195). What if he attempted to brainwash Goku through the voice of Chi-Chi or Gohan? Goku's outmatched here.
6 Can Beat: Eraserhead
Shoto Aizawa, the hero name Eraserhead, has a fascinating and powerful quirk. Erasure allows Shoto to nullify a quirk by observing a hero in his line of sight. Despite weaknesses, such as a need to blink, if we attribute Goku's powers to Quirks in this fight, Shoto would have a leg up, right? Likely not. Even without tapping into his more super-human abilities, Goku is a masterful hand-to-hand combatant and is incredibly strong without dipping into his power well.
That is if Goku wasn't already moving faster for Shoto to see.
5 Can Beat: Lemillion
Mirio Togata, aka Lemillion was one of the most powerful students at UA High. Was being a key term here because he was depowered in chapter 195 of the manga. With his Quirk, however, Mirio is a real challenge and a true hero. But his Quirk, Permeation, merely grants him intangibility. The big weakness, however, is that he has physical limitations such as a need to breathe.
Mirio cannot breathe or use any of his senses when intangible. He would need to deactivate his quirk, and that gives Goku long enough to do what he does best. As long as Mirio gives Goku an opening, Mirio is toast.
4 Can't Beat: Overhaul
Kai Chisaki, the villainous Overhaul, was not only a Yakuza captain but also one of the greatest threats the hero world ever faced in My Hero Academia. A brilliant criminal, Kai also had an extremely powerful Quirk. Overhaul, the Quirk, allows Kai the complete control of matter based on his touch.
He can disassemble and reassemble things entirely based on his whim. While Kai ultimately had his Quirk cut off at the root at the end of the Shie Hassaikai Arc. Provided he lands a single finger on Goku, it's all over for the Super Saiyan. Doubly so if any other heroes work their way into the battle.
3 Can Beat: All For One
The villainous All For One, Shigaraki, currently is imprisoned in the manga, but he is still incredibly powerful. His All For One Quirk allows Shigaraki to steal Quirks and use them as his own and bestow them upon others as well. All For One may be one of the biggest threats for Goku in these hypothetical matchups, but Goku should still handle the villain pretty easily.
All For One's "Impact Recoil" might give Goku a little trouble, but it seems that none of the banked Quirks is too overwhelming for the Super Saiyan. Goku probably wouldn't even need to go further than Super Saiyan 2, which occurred for the first time during the Babidi Saga in Dragon Ball Z.
2 Can Beat: All Might
As much as All Might is a paragon for power for good in My Hero Academia even his power has its limits. After all, it is because of his injuries that he ends up passing One For All to Izuku, kicking off the superhero career of "Deku." Even at his full strength, however, it seems likely that All Might may not be able to take on Goku. While One For All is a Quirk that offers All Might a near unlimited level of energy and strength, inherited from other owners of the Quirk, the level of destruction doesn't seem comparable to what Goku can unleash in some of his later forms.
Goku has taken on literal Planet Busters such as Frieza and outclassed them (Dragon Ball Z: Resurrection ‘F’). There doesn't seem to be much All Might could offer that is nearly as powerful.
1 Can't Beat: Eri
Perhaps the biggest upset imaginable is a matchup between Eri, with her Rewind Quirk, and Goku. Rewind allows Eri to reverse someone's body to a previous state. That means potentially rewinding a body prior to injury as she did with Deku during his Full Cowling. Her blood is even able to nullify the Quirks of other heroes, as was the major plot of the Shie Hassaikai Arc. She has even been able to rewind a person to non-existence, as seen in Chapter 156 of My Hero Academia.
Goku isn't likely to beat up a girl, so provided she is able to approach him and touch him, Goku could be reduced back to his childhood form, or even be wiped from existence. So yes, Goku can be beaten by a little girl, albeit an incredibly powerful little girl.