I'll give you the Naruto fight, because he was weakened ahead of time (although it was two hearts he lost, not three, he still had three of the five elements to draw one, plus two hundred years' worth of fighting experience, and he didn't seem particularly discomfited by it, but whatever), but not the other two. Unless my memory's failing me, there's nothing that indicates that Hidan was any weaker than Sasori, and in fact on a one-on-one basis I'd think that Hidan's ability is nastier; he hits you even once and you're dead, no questions asked. Yeah, Shikamaru used preptime and strategy to kill him; but that's just how Shikamaru rolls.

And as for Sasuke vs Deidara...yeah, it was close. So has been every significant fight since the very beginning of the manga. He still took Deidara down, one-on-one, and I really don't see what his status as a villain has to do with anything.

Yes, Pain won against Jiraiya and all that, but the fact remains that ninjas of Sakura's level are capable of winning in one-on-one fights against members of the Akatsuki. And considering the fact that up until the fight, Sasori's biggest (and only) feat had been defeating Kankurou, there was no good narrative or in-universe reason for Sakura to need help.