Seeing as Base Saiyans are way stronger than SSJ3 Gotenks, and Super Saiyan is still a tens of times multiplier, he probably solos Z.
That concept seems pretty weird to me, Goku is unable to teleport from Earth to Beerus' planet sensing Base Vegeta's ki until he went Blue, yet he is able to sense SSJ Trunks from that distance... It also depends on how strong you have Base Vegetto.
IIRC the Kaioshins were unsure if Vegetto could still become a SSJ, so Base Vegetto is at least equal to a hypothetical Goku and Gohan fusion.
Actually, they never give their thoughts on how things would play on Vegetto vs Buuhan, unless you refer to the anime situation. The last time they were shown was when they thought everything was over after Buu absorbed Gohan.
But, Gowasu later begged for pardon with Beerus for thinking that, "rival the gods" as well as "rival a god of destruction" is a ambiguos term, not to mention that during the fight between ssj God Goku and Beerus, it was said "surpass the level of the gods"... therefore, it goes nowhere. Gowasu thinking that SSJ2 Goku rivals Beerus is no different from Trunks thinking that Vegeta and Goku used their blue ki to fight the god of destruction (even then, Trunks is more reliable on this); they don't know the pattern of the events, as they were no present and just give their thoughts on what it were told to them.
From my understanding, that statement from Gowasu was used to indicate that the level Goku was fighting at was beyond the level that could be achieved by a mortal i.e "level of the gods". That should pertain to any level in Z.
The whole scene is about Beerus telling him that Goku had fought him before, then Gowasu asks himself how he could be alive and then after watching Goku overpowering Zamasu jumps to conclusions about that power of Goku could rival a God of Destruction, but then, Gowasu realized that he was in a mistake thanks to Beerus himself.
Even though, I agree with the idea that Trunks got stronger, it's still too much of a stretch to think that he had a difficult fight against Dabura and somehow managed to defeat him and Babidi to stop Buu's resurrection to surpass even Vegetto (this also discounting the possibility that Future Dabura can be weaker than Present Dabura considering the androids' case). Not even Trunks after training once more in the ROSAT didn't made that huge of a gains.
Gowasu sensed Goku's power and asserted that it reached the level of gods based on that. This is supported by Zamasu's response to Goku's power as well. The reason why Gowasu detracted his statement is out of respect for him. Gowasu was scared and wanted to placate Beerus. If you take a look at Goku's interaction with Beerus on the way back to Universe 7, Goku presents the idea that both him and Present Zamasu could reach Beerus' level one day which irked Beerus. There was some truth to the statement Gowasu made.
No, he sensed Goku's power increasing tens of times (as stated by Zamasu) from base to SSJ2. Zamasu was just amazed at how powerful a mortal can be, because they are gods and are supposed to be superior.. Yes, Goku stated that Zamasu can become a god as strong as Beerus and there's plenty of room for improvement, and his word is credible at some point; he's too strong for being a Kaioshin and is prodiguos at martial arts, but when you realize that afterwards, he felt in need to stole the body of a mortal, that he was jactancious that with his powerful body killed the gods of the other universes in the Trunks' timeline and that even Goku Black at his absolute strongest is still weaker than Beerus (which is an already confirmed fact) it losts all type of validity.
Well, Super still preserved the Gohan and Trunks against the androids special, Trunks states that he has gotten considerably stronger, even though he wasn't still strong enough to reach SSJ. Even after reaching SSJ he was too weak for the future androids, who in turn were weaker than the main timeline ones.
I just rewatched the scene and it definitely does seem appear like Gowasu claimed he was on the level of a God of Destruction strictly based on what Goku and Beerus had conveyed to him. However, Beerus does proudly acknowledge that Goku did fight Beerus and survived his battle against him which requires the viewer to understand the events of Battle of Gods. Those events clearly depicted Goku as a god level so that should remain consistent with SSJ2 Goku's power in the Zamasu saga. During the fight, Beerus smiles while viewing Goku's battle agianst Zamasu and even Zamasu is shook and claims, "This is the power of a human?!" a few times during the fight.
Many ideas were gathering in Gowasu's mind at this point in time, therefore, is logical to think that he wasn't making use of his senses properly nor was in a correct state of mind, as he wasn't concentarted. The whole reason Goku survived against Beerus is because he let him do so, he could've killed him at any point of the battle, he also pretended falling asleep when he had already won the battle and decided to not destroy the Earth, Beerus himself knows that wasn't that big of a merit and that was something he speak with Whis after everything happened; Beerus whole performance it's implied to be a lie and that he wanted to motivate him.
Well, Beerus smirking doesn't mean much, he had already smirked when Goku decyphered Time Skip and was proud of him. When it comes to Zamasu, his comment on Goku, just implies his inferiority towards him.
In Episode 47, Vegeta was training with Whis in Beerus' planet, yet, Goku couldn't find his energy until Vegeta transforms into SSj Blue and could teleport, in the next chapter, when Future Trunks came to the past while being unconscious, Kid Trunks transforms into SSJ in the garden and Goku teleport while sensing him.
He compared them, but previously he said that he hadn't fought a god since Beerus, so maybe that comparison is in regard to that and not in regards of power. Then, he states that Zamasu still is in a plenty of a room of improvement and can become a god as strong as Beerus.
I don't disagree with this but there were definitely narrative undertones regardless of Beerus' resentment towards Gowasu's claim. There wouldn't be any reason for Beerus to tell Gowasu about Goku's achievements if the viewers were meant to discard them. For one, Beerus conveys to Gowasu that Goku is no ordinary fighter before mentioning how he could fight a God of Destruction and Beerus was proud to admit this. And Gowasu was left with the impression that Goku was presumably fighting on a level that
He was smirking when Gowasu finally understood that there was a truth behind Beerus' claim. After all, the context suggests Gowasu was somewhat skeptical and confused. Gowasu begins to understand what Beerus was talking about once Goku overpowers his prodigy.
It doesn't really mean much. The Base Saiyans have battled opponents much stronger than SSJ Trunks. In fact, Base Vegeta was blatantly shown to be stronger than SSJ3 Gotenks.
