Power scale? So, in a scale of 1 to 10, 1 being I just got my ass handed to me by a toddler, 10 being I trample upon the gods themselves, I say 2B is about a 6? She's a badass, and I know for a fact that Platinum games actually went to a team of martial arts experts who specialize in performance to capture the movements of the characters, which is why she's so graceful, but in the roster of Platinum and other action titles she's not particularly above average. All her skills are great but not that unique, nor that OP. Compared to those robots, yeah, she is the very harbinger of death but those things are almost all pushovers.
Kratos brought down the Olympians, though having played those games I found all that rather underwhelming, (power fantasies, eh?) and Dante brought down the devil himself and more than a few like him, by contrast 2B's resume isn't as colorful. She's a great fighter, borderline dancer, but not sure she'd be able to topple gods.