An iconic shonen anime character, Goku, the protagonist of the Dragon Ball franchise, is often the centre of many arguments revolving around who he can and cannot beat. In this story, we too indulge in this argument as we come up with a quick list of the characters that we think can be bested by Goku vs. those who cannot.
Note: This list just contains the author's opinion and has spoilers for Dragon Ball, Z, and Super. Dragon Ball GT doesn't count since it's not in the canon continuity with the manga.
5 Dragon Ball characters that Goku cannot defeat alone
1) Jiren
Pride of Universe 11, Jiren was the last opponent standing in Dragon Ball Super's Tournament of Power for a very good reason. Considered the most dangerous and strongest mortal in the multiverse (at least until Gas and Granolah came into the scene), even Goku could barely tackle his solo.
Jiren was strong enough to rebuff attacks even when meditating, and would barely have to tap opponents in order to defeat them. Goku had to tap into Ultra Instinct for the first time to even make Jiren fight with effort, and by the end of the Tournament, it took all of Goku, Frieza, and Android 17s energy to finally knock him out of the ring.
2) Beerus
The God of Destruction of Universe 7 easily defeated all the Z fighters in both the Battle of Gods movie as well as the events of Dragon Ball Super (including Goku in all his Super Saiyan levels up to that point). Goku had to go Super Saiyan God and was, even then, handed a straight loss by Beerus. Training with Beerus is difficult too, as Goku is subject to all manners of intense and sadistic gravity.
Beerus is capable of taking chunks out of planets with his nails, and has had to have Whis fix a few. He was already a problem and it was only Bulma's food that ensured that no one would die. Fortunately, he chose to train Goku, but even equipped with Ultra Instinct, Goku still proves to be no match for him.
3) Broly
As if Broly utterly decimating everyone in his debut in Dragon Ball Z wasn't enough, Super has him more than able to beat down Vegeta and Goku at the same time. This big hulking rage monster Saiyan was already strong enough to stop a monster twice his size from a very young age, so by the time he got to Earth, he was able to keep up with Super Saiyan God Goku and Vegeta in his base form.
Broly going into his Wrath and first Super Saiyan form was enough to overwhelm Super Saiyan Blue Vegeta and Goku combined, along with Golden Frieza. It took Goku and Vegeta fusing to form Super Saiyan Blue Gogeta in order to match Broly, where they broke reality. It's clear that Broly would've died if that battled hadn't been concluded via Cheelai transporting him offworld, but Goku by himself would not be able to stop Broly.
4) Whis
The Angel Attendant to the God of Destruction Beerus of Universe 7, Whis is still far beyond Goku's abilities even at the present time in the manga of Dragon Ball Super. Being an incredibly powerful Angel, Whis has Ultra Instinct active at all times. He's been capable of dodging and barely tapping opponents to restrain and defeat them, and has access to powers beyond Beerus' reach, like time reversal.
Whis is currently Goku's mentor, providing Goku with guidance and training on the full properties and limitations of Ultra Instinct. When he and Goku spar, the results are always in Whis' favor due to his lifetime of power and godly ki, which is something that Goku has yet to fully master.
5) Fused Zamasu/Infinite Zamasu
Zamasu and Goku Black were already formidable opponents in Dragon Ball Super's Future Trunks arc, able to manhandle Future Trunks and only barely being stopped by Goku and Vegeta. When they fused, it took the Vegito fusion to damage them and Future Trunks to deliver the final blow there.
The problem then came when Zamasu began using his powers to influence all of reality. Zamasu had to be erased by Zeno along with Future Trunks' entire reality to truly be stopped, as Goku himself stood no chance. It's arguable that even with MUI, Fused and Infinite Zamasu would still prove to be overwhelming for Goku.
5 Dragon Ball duos that Goku can easily defeat
1) Jeice and Burter
The formerly fastest duo in the galaxy of the Ginyu Force were already no real match for Goku when he arrived on Namek during Dragon Ball Z's Frieza Saga. After managing to incapacitate Recoome with a single elbow strike in his midsection, Goku took on Jeice and Burter and handed them embarrassing losses.
While Vegeta was truly the one to kill both Ginyu Force members, Goku managed to down Burter with barely any effort. Nowadays, those two would be of no concern if they went up against Goku.
2) Future 17 and 18
The only reason Goku never fought 17 and 18 was because of the heart virus killing him in Trunks' timeline. If those two particular Android variants were to be up against Goku now, he would have easily won.
The two future androids were sadistic and cruel, killing off the Z fighters (Gohan included) before tearing apart the rest of the world. If they were time displaced, say into the current manga or anime timeline, and hadn't been killed by their current counterparts and went straight after Goku, their defeat would have been sure, given his Super Saiyan Blue and God modes. It can even be said that they'd be dead*.
*If anyone brings up the Dragon Ball Heroes multiversal tournament versions them, then it is crucial to point out here that DBH is not canon and those two weren't the same versions.
3) Nappa and Vegeta (Early Dragon Ball Z)
The first two serious villains to grace Dragon Ball Z after Raditz, Vegeta and Nappa weren't people to mess around with. They proved this with Nappa decimating the Z fighters, finally losing when Goku went Kaio-Ken and completely wrecked him.
Vegeta was a much tougher customer to handle, and Goku had nearly lost his life three times over, by then. However, this was pre-Super Saiyan Goku, and if that version of Vegeta and Nappa were to take on Goku now, they'd be dead or incapacitated before any of the Z fighters were so much as injured.
4) Tien and Chiaotzu
Tien and Chiaotzu started out as bandits scamming villages to make money in the original series, but slowly and steadily became good people, especially after being revived from their death from King Piccolo's attacks.
Both Tien and Chiaotzu were able to give Goku and Krillin a hard time during the Dragon Ball days, but then Z came along with the Saiyans, and things changed. Whilst they were at least able to handle the Ginyu Force, thanks to King Kai's training, both have been out of their depth since the Android Saga. Tien, at least, was able to stall Semi-Perfect Cell and prove his training during Frieza's invasion and the Tournament of Power but that still doesn't mean they'd be a match against Goku.
5) Goten and Trunks
Although not a particularly serious fight (Goten and Trunks are still kids after all), this would be considered something of a training session. It probably wouldn't swing the duo's way since they haven't kept up with their own training and are probably too young for the God ki training. Goku has shown the ability to handle multiple opponents, when, despite being exhausted in the Tournament of Power, he managed to defeat Caulifla and Kale.
Now, Goten and Trunks have the Gotenks fusion on their side, but even Gotenks has only gone SS3 at the most, and was manhandled by Beerus easily. That doesn't mean, however, that they can't put up a good fight, as 18 and Krillin did, during their sparring practice. It wouldn't last though, as Goku is currently well beyond the capabilities of the two young ones.