In what world was he fooling around against SSJ Goku? He even went as far as to say that he had to jump even further into the future because of SSJ Goku's performance. Whis also said that SSJG Goku was far superior to Hit. It's implied that Hit was close to SSJ Goku by Vados as well, saying that Goku would only lose because his stamina would drop first.
That's a translation issue. In the original Hit says he'll out-predict Goku's predictions.
"オレはその先を行くのみ / Then I'll just have to out-predict that."
"じゃオラはさらにその動きを予想すっぞ!! / Then I'll just predict your prediction!!"
Hit is pretty much playing along and seeing who can predict better. He's testing Goku just like before, except SSJ is obviously much stronger than Base. He's still waiting for Goku to transform right until the end, he should have a comfortable lead at the very least.
Not sure how to talk about Vados' line because Timeskip is confusing. Like, why is Goku more tired? Sure, the timeskip itself doesn't eat Hit's stamina, but he's still moving around and predicting Goku's movements.
Not true. We see the entirety of the fight. Vegeta flies over to Black after taking the senzu, has a brief exchange with him, and then Black starts pulverizing him.
Knowing how SSJB works, isn't that "brief" (we don't know how long it was) exchange enough for Vegeta's power to start decreasing?
I want to say Vegeta might have stomped Black before he got weaker, but I think that's something he'd show if it were the case. They probably fought evenly until Vegeta's power started to fade.
What implies using Blue in bursts offers that much greater power than the actual form?
It’s just them tapping into the power without the effect of drainage.
Also sustained blue is literally the perfected version.
The transformation alone costs Blue a lot of power. Using the bursts they turn to a lower form before the power fades.
With PSSJB, I guess the story tries to sell off PSSJB = SSJB bursts, but then Merged Zamasu just one shot Vegeta the moment he tried a burst.