Amuro Ray wrote:
All I can do is laugh at this nonsense - now you're twisting the story and adding in material that was never mentioned before to suit what YOU want it to say. It wasn't stated, and it wasn't implied at any point. I even posted the panels showing two different people commenting on his increased power, and the anime agrees on these
facts.
I pointed out before, Goku denied that he could have beaten BUU -
But later on with Vegeta present, he recants on his words and flat out admits that he could have beaten BUU the first time they fought. We see again seeing Goku claiming that they were no match for Buu, but a few panels later, Goku us soloing Buu by himself. We also have context clues that Goku is uncertain about his abilities in SSJ3 - it's not about pure output, it's about endurance, and Goku isn't sure he could endure the strain on his body.
That's not uncertainty at all. He said that he wasn't sure/couldn't defeat Fat Buu just to instill the need for the boys to master the fusion dance even more (in short, he lied to Piccolo, hence the grin). In his "recant" as you put it, he clearly indicates that part of the reason why he didn't defeat Fat Buu back then was because he wanted the boys to be able to handle it and not rely on him to win.
Chapter: 509 (DBZ 315), P11.4-6
Context: as Goku prepares to fight Boo
Goku: “Alrii~~iight. I’d better go all out right from the start…! If we get done in, then the entire universe will go ‘poof’…”
Vegeta: “Let me see this ‘Super Saiyan 3’ thing with my own eyes…”
Goku: “Is that alright? You just might not get your turn…I can say this now, but the truth is that with that fat Boo, I would have been able to defeat him at the time with Super Saiyan 3…However, I wanted the young guys to manage something…For the Earth’s sake too…”
This means that he knew full well he could have defeated Fat Buu when he told Piccolo that he didn't think he could, thus he lied to him about it, and in turn wasn't unsure of his strength at all.
It'd be one thing if Goku actually physically fought Evil Buu after he made that comment, but he never did. It's clear that Goku's entire confrontation with Evil Buu inside Buu's body was a bluff on Goku's part. He had absolutely no reason to lie to Vegeta about their chances at defeating Buu on their own, but had every reason to lie to Evil Buu about how powerful he was in order to try and bluff his way out of a confrontation. He knew full well he stood absolutely no chance of actually beating him in a one-on-one battle, or even a two-on-one fight with Vegeta assisting him, but he was hoping that his feigned confidence would convince Buu of how powerful he was.
Vegeta clearly indicates as he and Goku are watching Buu revert to Pure Buu that he's undergoing another transformation after having first seen him revert from Evil Buu to the "Buff" Buu form he had when he absorbed South Kaioushin.
Chapter: 508 (DBZ 314), P2.3-7, P3.3
Context: after reverting to his South Kaioshin form, Boo continues to change
Vegeta: “…Look…He intends to perform another transformation…”
[ ]
Goku: “…I wish he’d cut that out…”
Kaioshin: “Th-this can’t be…it’s impossible…He’s cha-changing back…”
*Boo changes back into his pure form*
Kaioshin: “…I…I knew it…”
So this is taking place after it's stated that he's getting stronger, so he has already transformed into the state that they said was "getting stronger".
Then, after he's finished with the second transformation, Goku and Vegeta have this exchange.
Chapter: 508 (DBZ 314), P3.4-6
Context: after Boo reverts to his pure form
Goku: “…”
Vegeta: “……Heh…Heheheh…Look! He’s shrunk down quite a bit!”
Goku: “We did it! This way, we might be able to manage something.”
What were Goku and Vegeta setting out to do earlier that he'd feel the need to exclaim that "We did it!" and they might be able to manage something? Weakening Buu down to where they'd be able to fight him as they are and not need to fuse.
Chapter: 506 (DBZ 312), P12.4-5
Context: after Goku and Vegeta revert Boo back to regular evil Boo
Goku: “Hehhe~~eh! With this, Boo’s power should have fallen significantly! We’re almost there! See, see: the size of his ki is completely different than before!”
Vegeta: “Alright! Let’s blast out of here and escape!”
Goku: “Wait! Even though Boo has returned to normal a whole lot, we’re still simply no match for his strength! If we go outside like this, we’ll definitely be done in…!”
So even excluding the line that you keep saying is irrelevant, it's clear that Goku and Vegeta were removing cocoons to weaken Buu to where they would be able to fight him with any chance of winning, and it was reverting him down from Evil Buu to Pure Buu that Goku finally felt they had achieved that.
Evil Buu ("we're still simply no match for his strength!") transforms into Kaioushin Buu (“H-hey…Vegeta…His ki is increasing, ain’t it…!?”), indicating a power increase.
Kaioushin Buu (“H-hey…Vegeta…His ki is increasing, ain’t it…!?”) transforms into Pure Buu ("We did it! This way, we might be able to manage something.") indicates a significant power decrease.
As such, Pure Buu is significantly weaker than Evil Buu.
Everything I've said is in the manga. I'm not adding things or twisting things to try and make my side of the argument more convincing.