My problem with Gohan becoming Goku's level is that there is no reason for him to be.
He was a good character, and the anime showed that it was not necessary to be a top tier of the verse again to have things to do with him.
Superhero decides to take all of Gohan's development in Super (mostly the anime, because Gohan is treated horribly in the manga, prior to the Moro saga) and throw it in the trash to restart it again.
Let's talk about the Anime version:
He began to have a normal life, with his wife and daughter, stopping training, and... them Freeza gave him a beating in the resurrection of F, both emotionally and physically:
- He could barely use the Super Sayayin, he didn't even have his Gi.
- At the moment of finally doing something, he is suddenly tortured by Frieza (because he momentarily acted as his father, activating Frieza's trauma).
- Almost dying, he only survives because Piccolo sacrificed himself for him again, making it clear to what extent Gohan had fallen.
- He was left out of combat by taking out more Ki than that of Supersayayin 1, that is, in the end it was not even Frieza who defeated him, but himself, to be able to bring Goku and Vegeta
- The earth is destroyed, losing his own family for whom he stopped training to have a normal life, only being saved by going back in time,
All of this ended in Gohan deciding to train again to protect those he loved, realizing that he cannot put aside his warrior side, a conviction that increases in the Future Trunks saga, upon finding out what Trunks was going through, and feeling guilty. Because he did not realize that,when Trunks visited him.
He trained more seriously, and when he finally said goodbye to Trunks, Trunks saw his teacher (future Gohan) reflect in him, despite previously having thought that he was the complete opposite of Gohan. (Also, Trunks previously understanding what half of the DB fandom cannot, and that is that Gohan not being like his version of the future was fine, since the Gohan of the future is the consequence of losing his loved ones and his dreams)
Finally for the tournament of power, with a threat to destroy his entire universe, Piccolo makes clear to Gohan his mistakes as a fighter of becoming arrogant when he has the advantage, and Gohan ends up becoming the best version of himself, and still aiming higher, thinking in finding his own path, as a human instead of a sayayin, earning his father's respect as a warrior, and ending up being the leader of his universe team, being the most intelligent of them.
On top of that, the anime makes it clear that having your own life outside of fighting is fine, and shows us that although Goku doesn't understand it, he respects his life decisions and his work (understanding when Gohan couldn't go to the universe 7 vs universe tournament 6, making it clear to him that his things came first, before the fights).
What does Superhero do?
- Gohan has stopped training again, with the excuse that Goku and Vegeta will take care of everything in the end (Destroying all of Gohan's development in Super)
- He becomes a bad father, focusing on his research, not taking time for his daughter, not even going to see her at school, to the point that his daughter doubts that she is loved by him (since we are, I imagine that he is not taking time for his wife either) Ignoring the bases of Gohan's character in Super
- The entire movie treats the fact that Gohan works poorly, as if it were still a mistake.
- Piccolo's plan is to appeal to Gohan's fury to return him to his final state, even though a large part of Gohan's development in Z was learning to control his emotions,
- The beast Gohan makes no sense, and the Gohan who aimed to evolve as a human ends up having a transformation that is basically the super sayayin but stronger and with another name (Destroying all the potential of Gohan's character for the future)
The biggest mistake of the Superhero movie is Gohan, I think the movie itself leaves the theme that he does not pay attention to his daughter in a, "he has shown her that he does love her by saving her" something that the manga at least dedicates to him a vignette saying "maybe I should pay a little more attention to my daughter" (the manga version of the movie is undoubtedly better than the movie itself, but that's not saying much)