Supergirl. Candor arc, when they are suddenly shown out of the bottle city. As I said, there were extenuating circumstances, and PG meant right then, at that specific time, not in general. Just as Supergirl meant it that way at the start of her series. I will not that I do NOT like that version of Supergirl. She was violent, borderline nuts, and a pretty nasty piece of work who didn't seem to see other people as...people, but rather as objects. Either that, or she got off on hurting people. She had Power Girl in her biggest weakness, a full nelson, and threatened to break her shoulders...this right after she abandoned Power Girl to the bad guys and let her get tortured and nearly murdered. PG could not escape the hold because she apparently has brain damage and forgot everything she was taught about getting out of that move, every time someone uses it on her. PG commented on how strong SG was, and then SG noted it was lucky PG wasn't at full strength.
Regardless, SOMEONE has to teach Power Girl how to get out of that move. A person capable of fighting Wonder Woman very well shouldn't let that be everyone's go to move for beating her...
Seriously, what's up with that?
As for the Supergirl stronger than Superman thing..they sort of retracted that fairly early on in the Supergirl series. Something like Superman always holds a lot back, while SG doesn't hold anything, or some such. Struck me as a belated realization that maybe they made a mistake.
Personally, I agree with you, Power Girl should be stronger than Supergirl...and a MUCH better fighter. Faster too. I'm just saying there isn't any real evidence one way or the other....YET! Hear that, DC? Bring back PG and then make it so!
The point being that there has been no definitive statement by either, even though they've both ventured an opinion.