Vegeta believed he would win if transformations weren't allowed in the tournament. And Dabra and Babidi believed that the base Saiyans' energy was better than Piccolo's.
So for the base-level Saiyans to have surpassed Piccolo by the Boo arc, it means their powers would've needed to increase by well over 50x... And considering that 2-4x increases in power(ie. SS2 and SS3) were still considered to be absolutely gargantuan amps during these sagas, it's hard to believe the Saiyans had powered-up that much in their base forms.
The fact that Bootenks reverted to Booccolo helps support this notion. Per the Daizenshuu, Goten's power was equal to Gohan's at the start of the Boo saga, and Trunks was marginally above Goten. IOW, Trunks ~/> Goten = Gohan(pre-unlock). So if the Saiyans were that powerful in their base forms, Bootenks should have reverted to a Trunks-esque form instead of Piccolo... But he didn't.
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I'm sure Boo could have accessed their SS transformations if he had tried, but that's not what I'm referring to here.
When the fusion timed out within Bootenks, the boys defused into their base forms: (please log in to view the image)
And given that the Daizenshuu has Goten and Trunks equal to pre-unlock Gohan, Bootenks should have reverted into one of the boys' forms, IF indeed they were actually above Piccolo in their base states... But again, he *poofed* into Booccolo instead. This heavily suggests that Piccolo > base-level Goten/Trunks(and therefore pre-unlock Gohan.)
Aside from that, in the scene Marikina was presumably referring to here:
Dabura mentions that "three of them"(ie. Goku/Gohan/Vegeta) have "great potential", which is why he [correctly] believes they should be the primary targets for energy-drainage: https://ibb.co/WfcYvhx
Imo, this implies that Dabrua [correctly] sensed/deduced something deeper within the Saiyans than just their base-level power.
tl;dr
That scene doesn't really paint an irrefutable picture that the base Saiyans were meant to be above Piccolo in the first place. /shrug
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
Vegeta would definitely beat Goku without transformations at any point in the series, he's a full blooded elite Saiyan and naturally stronger than low grade trash like Goku. It's the transformations and all that divine coaching he got that made up the difference.
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Well I personally don't think Beerus was actually deducing Goku's power, during the scene in question. I think he was just interested in pointing out that the Saiyan's had other forms he didn't previously know about.
Anyway, Goku in base during RoF was able to effortlessly manhandle Frieza in Final form, who in his first form was literally thousands of times stronger than his Final form on Namek. And Frieza's final form is roughly a 226x boost to his first form, granted that on Namek he went from 530,000, to 120 million.
I don't think Goku could have gotten literally MILLIONS of times stronger in his base form, during the time between BoG's and RoF. Which would be the only way you could explain him being weaker than final form Namek Frieza in BoG's, and suddenly manhandling a Frieza who was easily thousands of times stronger than before.
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