[list][*]Goku outright tanking a charged blast of one of the strongest techniques of Piccolo
[*]Base Gohan (post unlocking Mystic) and Base goku are equals, and Base Gohan in current battle Royal appears to be better off than Piccolo.
[*]Goku wasn't even serious when sparring against fit buu, who he called superior to fat buu
Such as Piccolo being vastly superior to Super Saiyan Gohan who is superior to base Goku who transforms into a Super Saiyan to face him, instead of suppressing his base form (with an extreme suppression, in fact, supposing he can beat the Super Saiyan 3 Gotenks of the Buu arc by lifting a finger or so).
The idea that he would go Super Saiyan and then suppress his Super Saiyan form to below base levels is filmsy to say the least. All the other instances have been throughly proven to be 100% inconclusive and much easier to justify in this very thread countless times, either by me or other users; I'm absolutely not gonna go through them again. They can all be justified by characters (Goku or whoever is fighting) suppressing themselves or not seriously trying to hurt each other, unlike Goku vs. Gohan from before Gohan re-trains, obviously, which would makes Goku simply act in an incomprehensible fashion for the viewer or just "incomprehensibly" in general. Base Gohan has also done virtually nothing which would put him above Piccolo in the tournament, so I don't understand what should be the reference here.
Considering the fact that Base Goku was capable of blocking a charged blast from Piccolo, something you conveniently ignored, then yes there is evidence that Goku>Piccolo.
And on the Base Saiyan argument, every argument against Base Saiyans being high (above SSJ3 Gotenks at least) I've seen involves a lot of head canon or special pleading. The show has made it very obvious that the base saiyan's are much, much more powerful than they were in Z. Even ignoring the fact that Goku's Base is more powerful than BOG saga SSG Goku, the Copy Vegeta fight should have made it obvious. There was no reason to believe Gotenks got any weaker, or that there were two bases, or that Copy Vegeta was any stronger than regular Vegeta.
First off I didn't "ignore" anything, much less "conveniently", as I had originally stated that there was simply more
evidence in favor of the opposing argument. Secondly, I've explained my rationale as to why Gohan vs. Goku would normally take precedence to me in very clear terms in the post above. Since this thread has this rather serious problem - especially for its habitues - of regurgitating the exact same arguments
every dozen of pages (and usually with some pretense of total conclusiveness on this
issue), I'm just avoiding the nth
repetition when trying to contextualize Goku's supposed feat against Piccolo in the mock fight (which not only wasn't even referenced in the post I was quoting, but was also at least indirectly addressed in the very post you
Thirdly, following your own premises, one could pretty much be able to make an exact same argument: "Goku's apparent inability to beat opponents vastly inferior to Good Buu when he should be far above the SS3 Gotenks we knew from the Buu arc makes the theory he's really above him headcanon"; a very similar conjuction applies to Goku turning Super Saiyan to handle Gohan in the first place, however. I wouldn't exactly venture towards the usual "you're all in denial" undertone, since it's even technically easier to turn it the other way around.
By the way, I'm fairly sure not even "Beyond God" Goku from ROF is stated to possess power superior
to that of the Super Saiyan God seen in BOG. Super Saiyan Goku is equal to God or a little weaker than that when he's fighting Beerus, and his regular form should be 1/50 of that.
If you're using some statement from ROF, chances are you're using one of the wrong translations that has Krillin says Goku's using "more power" - or a similar spiel - in base than what he did against Beerus (whilst Krillin actually says that he gets a sense of "real dread" from the fight and nothing more).