Yeah... I guess this won't go anywhere, since you want to question direct statements that aren't hinted at all to be questionable.
You are weirdly taking the character statements as the final truth when time and time again they are shown wrong.
Goku states his SSJ3 could have defeated Buu. Later on, he cannot defeat it as SSJ3. The time limit on Uranai Baba's power is roughly equivalent to Goku not being able to summon enough power to kill Kid Buu so I have to assume he is wrong. Of course Goku would have wanted ideal conditions of unlimited time with his undead body, but he cannot arrange this, so for all intents and purposes SSJ3 cannot defeat Buu.
If you standard of "the statements aren't hinted to be questionable" holds, what do you make of Majin Vegeta vs Goku? Vegeta thinks he has finally matched up to Goku. There's nothing in that fight hinting of Vegeta being wrong, or Goku having SSJ3. This is clear proof that Toriyama doesn't care about hinting whether what anyone (in particular Vegeta) says or think is wrong. Toriyama does not give a fuck about hinting.
Vegeta is wrong about his opponents' strength twice during the Buu saga alone (during all of dbz Vegeta is constantly, hilariously, sometimes massively wrong about this). His self immolation is not even close to killing Buu, and he doesn't even notice that Goku was holding back massively during his Majin duel (something that is not even hinted). So you gotta admit that Toriyama writing a Vegeta being wrong about Gohan being out of shape, could have easily be Toriyama making Vegeta wrong again. Shortly afterwards, once Gohan is dethroned from the protagonist role, Toriyama will go out of his way to show Gohan is weaker, twice, but the "out of shape" comment is par for the course for Vegeta.
Gohan's potential unlock in the Namek Saga was pretty pointless though,
Not as pointless as Mystic Gohan.
All in all, Gohan participation in the Namek saga is of much more importance, weight and entertainment value, all without the need of weakening him. Gohan is also given more agency in Namek, agency that will be slowly taken away during Cell (in which he does _zilch_ before the actual defeat of Cell) and by the time of Buu, Gohan is super passive.
but that "What If" scenario is irrelevant. What I'm pointing out is that Toriyama clearly was building up to them from the beginning of the Buu Saga - Gohan's weakness first mentioned two chapters in, he's out of practice in the beginning of Goten's training, then finally Goku and Vegeta see that he can't match his previous full power when powering up to his maximum, and Goku tells him (and Gohan tells himself) to remember his anger to draw his hidden powers again like he did against Cell. Eventually we get those hidden powers coming to play again with the Ultimate form.
So, the existence of that foreshadowing breaks the idea of an aborted Saiyaman arc. Obviously, at this point, it's clear you won't accept my conclusion, since you're even willing to question the manga's characters themselves even when the manga didn't, but I want to make my point very clear before dropping this. You're focusing on why you think Gohan isn't main character material, my focus here is on signs of changed plot threads or foreshadowing.
Your conclusion is not acceptable because you are conflating two different issues; the idea of Gohan being weaker and the idea of Toriyama having a different plot charted for Gohan, which may or may not have included the Great Saiyaman. Let's _assume_ it would have included it and that Gohan was intended to be weaker.
There's nothing saying that a weaker Gohan couldn't have had further adventures as Great Saiyaman. The two concepts are not contradictory. The facts are that the great Saiyaman stuff is aborted by the tournament arc super early, around same time that Goku takes back the reins of the series (namely, his "fight" with Kibito).
On the other hand, if Toriyama had something else planned for Gohan (let's say, a longer Great Saiyaman arc) that he changed in favor of Goku, those plans would have left behind dangling plot threads when they were cut in favor of Goku. I will show where this _clearly_ happened.
For starters, it is weird that Toriyama had spent some chapters setting up Gohan's secret identity and his school mates, just to waste it all on Kibito's fight. Specially considering that very fight is where Gohan stops being the protagonist. Toriyama fucks around a lot during the actual tournament (those chapters are pretty aimless), and it is clearly the Spopovich/Videl and Kibito/Gohan fights where he decides to get the plot going.
Your idea that the "out of shape" comment "breaks the idea of an aborted Saiyaman arc" would mean that Toriyama planned on fucking up Gohan against Kibito from the very start (given how Vegeta upgrades his "out of shape" comment into "weaker than during Cell", which, if we accept your idea of it being foreshadowed, means the Vegeta comment was planned beforehand for this very fight), which would be weird as that fight marks the point where Goku steps in as protagonist.
The problem is that, by the time of "out of shape" comment, Toriyama still was trying to write Gohan as a protagonist. Why would Toriyama be planning on how to undermine him at that very same time? Gohan-as-protagonist will last a few chapters more after that comment.
It is much more probable that Toriyama just used the Kibito fight to abort the whole Great Saiyaman plot, tired of trying to write Gohan in the lead role. The proof is that the GS plot leaves behind some dangling plotlines that go nowhere. His schoolmates won't be relevant (or shown?) again after it. Gohan worries about "his secret identity being blown" and "not being able to live a normal life", which is very adequate for a superhero story (Toriyama's possible original plan), but these plot points are not ever brought up again, not even in the epilogue. So those are the dangling plot threads that won't be followed up upon, the evidence that the GS was planned to go on longer.
Oh I forgot a detail in your previous post
No, this is very important. Yes even if Gohan had his Cell Games power, he wouldn't be strong enough, but that's irrelevant. What I'm pointing out is that his decrease in power leads the other characters to talk about his hidden powers from the Cell Games and tell him to awaken them again. This eventually leads to the Z Sword and the Kaioshin. If you remove Gohan's weakness, telling him to awaken his hidden power wouldn't make sense, so they'd only be mentioned once we got to Kaioshin, removing the build up to it all.
Gohan's weakness, which is first mentioned in the 2nd chapter of the Buu Saga leads directly to his old hidden powers being mentioned again, and afterwards they're once again relevant with Ultimate. I think those plot threads aren't disjointed or a coincidence, but clearly build up and foreshadowing, which couldn't be done if Gohan weren't weaker. I think it's clearly a stronger line than the idea of some aborted Saiyaman Saga (in spite of the lack of foreshadowing or build up to any conflict in those chapters).
This is factually wrong. Kaiohshin is interested in Gohan's hidden powers when he brings him to kill Dabura and stop Buu from coming out, yes, but Gohan getting the power unlocking has NOTHING to do with him being weaker than during the Cell saga. The old Kaioshin just picks him up for the ritual because Gohan was holding the sword when it was broken, thus marking him as the one who freed him. That's all there is to it. Cell, or Gohan having become weaker is not relevant at all to the Mystic Form. If you remove the Vegeta lines about Gohan being weaker, Gohan still gets the Mystic form without any problem (because even Vegeta, who is stronger than Cell's Gohan gets rekt by Buu, so even if Gohan had kept training in the meantime, he would have been wiped out too, leading to his rescue by Kaiohshin/Kibito, who still had use for a guy stronger than himself).
Which means the drama of Gohan having become weaker since Cell only works until the Dabura fight, and the only thing that it serves is making the public pay attention to Goku and Vegeta, as they are clearly stronger and thus more interesting. Vegeta comments to Gohan having become weaker only purposes is to draw the public's attention to Goku and Vegeta (and are timed to this purpose, as the first time happens just before Goku decides to follow Kaiohshin, and the second time around the Dabura fight, just before the Majin Vegeta/Goku fight).
But this is all way too far from the original argument, that Toriyama took away the leading role from Gohan and gave it to Goku super early. The proof is that Gohan super early is reduced to taking orders from other people, and that Goku is written as the one taking matters on his hands at the very first opportunity provided (helping Kaiohshin). And that this process of taking away agency from Gohan starts as soon as the fourth episode, at the very same time the Great Saiyaman plot is cut short and the tournament is given attention and Goku is announced to come back.
That is how early Gohan stops being the protagonist (the tournament stuff is all very wishy-washy, with the characters just walking around and talking, yet Goku still gets more panels than Gohan before 444, even considering that 443 is an almost all Gohan chapter). In 444 Goku takes the lead and never gives it back, while Gohan will have to content himself with looking at his father all dumbfounded.
The original claim was that Goku took the lead super late and that Gohan was supposed to be the hero all that time, and that is obviously wrong. Toriyama notices he cannot write a protagonist Gohan very early (as soon as 425), and then spends a dozen of chapters waving his hands until he can give the protagonism back to Goku.
