In the world of shonen anime, most of the present protagonists aspire to be the very best or the absolute strongest in their respective universes. Yet there are others that, even when they get stronger, are not the strongest in their universe or are on a lower level than the villains or even other heroes.
Even shonen anime protagonists like My Hero Academia's Izuku Midoriya aren't immune to this, as even with the power increase, there's always a bigger fish. Befitting the nature of shonen anime, there's plenty of serial escalation that forces the heroes to get stronger.
Note: This article is going to contrain spoilers for many popular shonen anime and represents the author's opinion.
10 shonen anime protagonists who have a long way to go in their universes
Despite Goku having helped win the Tournament of Power in the shonen anime Dragon Ball Super, he isn't a god or the strongest in his universe. That may be shortchanging or otherwise underestimating Goku, but he has struggled more often than not. Throughout Dragon Ball, he went from a kid able to down a giant fish to a fully grown adult capable of beating King Piccolo with extreme difficulty.
By the time of Dragon Ball Z, he needed Piccolo's help to stop Raditz. Even with the training he went through with the Kaio-Ken technique, he wasn't able to stop Vegeta without help since the character cheated to go Great Ape.
Despite Goku defeating Burter and Recoome, he needed a soak in a healing tank to heal before his battle with Frieza. There was the heart virus that debilitated him during the Android saga, he couldn't beat Cell even at full power, and the Buu saga needed him and Vegeta to fuse and even then he needed a Super Spirit Bomb to beat Kid Buu.
In Super, Goku lost cleanly to Beerus, would've lost to Broly if not for Vegeta fusing with him, got clocked by Jiren, nearly died against Moro, and is still struggling against Gas in the manga.
The point is, Goku's been tossed about time and again even after gaining Super Saiyan 1-3, 4 in GT, and God and Ultra Instinct in Super. There's nothing wrong with needing help in shonen anime, period.
The sheer amount of fans overestimating Goku as a single fighter and ignoring the entire context gets very ridiculous at times. Teamwork is usually what prevails for many shonen protagonists after all.
2) Boruto Uzumaki
The lead of the shonen anime Boruto: Naruto Next Generations is hardly the strongest person in his own shonen anime. That's the point, as Boruto has a long way to go before he's a serious contender for Naruto's level of power.
Again, not that levels of power mean anything in the Naruto universe since even the most powerful person like Isshiki Otsutsuki was brought down by Baryon Mode Naruto and Kawaki stalling until the aging power brought him down. Even then, Kurama died to stop Isshiki.
The addition of Karma and Momoshiki possessing Boruto's body would definitely push him up a few degrees, plus being the one to beat Momoshiki with Naruto and Sasuke's help is a plus.
Point being, the kid hero and actual protagonist of the show isn't the strongest person alive and his story is still going on. Beyond the Karma idea, Boruto's own abilities are growing exponetially with his own Rasengan and eye power control.
Now, does this mean he won't get stronger in the future? If the time skip at the beginning is any indication, he will get strong enough to battle Kawaki one-on-one. The audience is just watching Boruto grow up as a person and as a fighter. He may end up surpassing Naruto after all.
3) Joseph Joestar
The lead protagonist from the shonen anime JoJo's Bizarre Adventure's Battle Tendency arc is the only human in his own series. Even in his own universe, he is arguably the weakest of the Joestar line. Despite his Hamon/Ripple abilities and his brains, Joseph doesn't advance in power beyond his peak in Battle Tendency.
The point is that JoJo doesn't really have that huge a power scale compared to other shonen anime like Bleach or Dragon Ball Z. People win in that universe by being clever, whether as a Stand user or not.
In that area, Joseph tends to succeed as he was able to beat the three Pillar Men using his head and the right application of Hamon/Ripple.
As he ages throughout Stardust Crusaders and Diamonds is Unbreakable, his wit is still with him even if Hermit Purple isn't the greatest Stand. His notable accomplishments as an older man are getting rid of two Stand users in Stardust Crusaders, and rescuing and adopting the Invisible Stand using baby in Diamond is Unbreakable.
4) Izuku Midoriya
What would a list like this be without Izuku Midoriya aka Deku from My Hero Academia? Nothing, that's what! Deku started out as a shy, Quirkless kid who could barely stand up to his bullies and had crippling self-esteem issues. Thanks to an attempt to save Bakugo that resulted in All Might getting his attention, Deku was given the power of One for All.
As is the case with most shonen anime protagonists, Deku was barely able to control his newfound power without injuring himself, even after intense training.
Over the course of the series, he got more skilled with his Quirk, able to stand up to villains like Muscular, Overhaul, and even Tomura Shigaraki.
Of course, in order to beat Overhaul he needed Eri's help to boost his power without dying. He had to help Bakugo out of the League of Villain's clutches and would've been crushed by Nomu if not for All Might and the rest of Class 1-A's help.
Plus, there was also the part where Class 1-A had to fight him to calm him down and prove teamwork matters more than individual power, even if Deku had access to a ton of quirks.
5) Edward Elric
Despite being highly intelligent and an otherwise great fighter, shonen anime protagonist Edward Elric from Fullmetal Alchemist has lost or barely survived fights with people like Scar and the Homunculi.
Edward learned martial arts and alchemy at an early age following his mother's death. After he and his brother Alphonse trained to use alchemy under Izumi Curtis, the two attempted to revive their mother using their knowledge of alchemy.
To say that it didn't work would be a massive understatement. As Edward and Alphonse had to adapt to their new bodies and mechanical prosthesis, the two honed their alchemical skills to try to get stronger in order to get their bodies back.
Edward himself faced off against many from Envy to Father and nearly lost his life in the process.
Even when fighting against Father, who could control every facet of Alchemy, it took a combined effort of multiple state alchemists and non-affiliated alchemists alike to finally put him down in Brotherhood. In the 2003 version, Edward died against Envy but was revived in the 'real' world or it's closest approximation.
6) Ash Ketchum
Though considered the poster boy for wanting to be the very best, Ash has lost as many battles as he's won. In the shonen anime, Pokémon, Ash Ketchum is usually memed as a loser despite coming closer and closer to his goal as the various adaptations wore on.
From the first loss to the gym leader Brock in the Kanto region, to being thoroughly trounced repeatedly by Paul in the Sinnoh region, Ash usually takes these losses as inspiration to keep going.
Ash has proven his mettle against even the toughest Pokemon trainers and Gym Leaders, only being stopped in League battles.
It wasn't until the Alola region in the shonen anime Pokémon the Series: Sun & Moon, that Ash finally became a Pokemon League Champion. It was a huge moment in anime history for fans of the character, but it's worth noting that Ash had to go through powerful people along the way, and is still not number one in the universe.
7) Rurouni Kenshin
The wandering samurai and former manslayer Kenshin Himura was certainly a skilled swordsman of great infamy when the series began as he slew many people during the Meiji Revolution. Despite having access to speed so quick as to dodge gatling gun fire, Kenshin has prefered to be quick and nimble in battles and end things in one strike.
If battles are prolonged, especially if the opponent is skilled enough like Shishio is, Kenshin risks his techniques failing, along with his moral code.
Since giving up the manslayer title and attitude, Kenshin has struggled to control himself and not revert to more lethal attacks and ruthless aggressive actions.
While Kenshin is very good at sword fighting and unarmed combat, he has been caught off guard against Shishio and people using guns. The only other thing is that he desires a peaceful life, which leads to him giving up the blade at the end of the series and living in peace with his wife Kaoru and their son Kenji.
This magicless protagonist from the shonen anime Black Clover gains more power from anti-magic and is still not the strongest in his universe by a long shot. What's notable about this particular shonen anime protagonist is that, like Deku, he starts with a disability (having no magic at all when everyone else does) and still has that disability even with the levels of anti-magic power he attains.
Asta operates at a different level than everyone else, having to struggle to accomplish things that many magic users take for granted, which makes him an underdog.
One example is his solution to the high Mana volcano, since it cannot be surpassed without magic. Asta's solution? Run up the volcano fast enough that he doesn't burn to death.
Asta may have started as a loud person, but he does learn how good teamwork can help via getting beaten a fair few times. Even during the battle with Lucifero, Asta required the aid of all his friends and companions to damage the devil and help him power up his Anti-Magic sword. It was still a close fight, but good triumphed in the end.
9) Ippo Makunouchi
Another person without superpowers, and one who is far from being the strongest in the universe, Ippo Makunouchi starts out being the son of fishermen and has the question of "What does it mean to be strong?" playing in his mind. The shonen anime Hajime no Ippo features his journey from a bullied kid to a Featherweight Champion.
Though Ippo's win-loss record is 23 wins to 3 losses in official matches, those wins weren't easy. He had to go up against opponents faster than him, more powerful than him, and smarter than him too.
Despite his punching power being one of his biggest strengths, his footwork suffers as a result and his speed isn't great unless at close range.
This puts him at odds when it comes to boxers like Sawamura, a savage and cheating boxer who intentionally went for painful blows. Ippo would eventually become Featherweight Champion, but would retire after six years in and out of the ring. It's just as well, as learning when to stop is always something shonen anime protagonists can learn.
10) Gon Freecss
Gon Freecss is one of the leads of Hunter x Hunter, and isn't the strongest person in his universe by a long shot. For one, there's Hisoka, who Gon vowed to defeat but hasn't. For two, Killua had him beat in terms of speed. The third is that Gon lost his Nen abilities after the Chimera Ant arc.
Gon had the powers of Nen, granting him enhanced strength and punching power. His arsenal of abilities were close-ranged, and his full spectrum of power was only unleashed after the Chimera Ant arc.
He's been overwhelmed and defeated before, though has always gotten back up.
The vow that this shonen anime protagonist made upped his power by a lot, similar to going Super Saiyan. The problem is that it also shaved off his lifespan and put him into a coma. Were it not for the aid of his friends he'd be dead from the drain the power boost took.
While unable to use Nen or sense aura, Gon devoted his time to studying. It just goes to show tapping into full power when you're not ready is bad for shonen anime protagonists.
Poll : Do these shonen heroes fit the 'not strongest' definition?
All of them do.
Some do, some don't.