Powegirl regains her strength after each victory. How far does she get?
1. Giganta
2. Red She Hulk
3. Valkyrie
4. She Hulks Lyra & Jen
7. Starfire
8. Supergirl
9. Wondergirl and Donna Troy
9. Big Barda
9. Cheetah
10. Wonder Woman
3 is where things could get troublesome from Karen as Dragonfang could be a problem if Valkyrie manages to score a direct strike on her with it. Starfire's powers could be an issue if she attempted to attack Karen's solar reserves. Supergirl is likely to be a tough fight, but Karen's raw experience and skill should prevail ultimately. I don't see her beating Donna and Cassie at the same time, though. Big Barda's likely going to beat her. If she plays smart and range spams, she'd beat Cheetah. And Diana's skill over Karen is what ultimately causes her to lose to Wonder Woman.
All in all, Power Girl could fight any single foe here on even ground for a time, though.
Your numbering is weird (Not the foe order- that's good, just not the numbers themselves)
Wondergirl and Donna Troy is where she probably stops. Valk and Star and Supergirl are threats, but she's got a clear edge on them.
Her best bet against Cassie and Donna would be to take out Cassie ASAP, because one on one she can take Troy, it's just doing so with backup that's a big problem.
Well, Starfire should be the point where she can't realistically win. Kory drained Zod's army force by her lonesome. A quick drain and a few punches should down PG.
If she were to beat Starfire, she'd probably beat Kara and lose to Donna and Cassie.
I'd say she gets too cheetah. Too be honest, it can go either way. However, Cheetah's current upgrade has given Diana problems so...
Anyway, when it comes to female superheroes I'd place Karen right below Wonder Woman, Star Sapphire and Maxima. I think her flight will give her the upperhand against Barda. To be honest, I have yet to be impress with Barda. I haven't seen her perform high feats.
Kara's never demonstrated that kind of speed, unless your counting flight; however, Kory has ftl flight speed too.
One punch isn't going to KO her anyway. She's taken hits from Superman, Wonder Woman, etc. and got right back up. Kara's way stronger, but Starfire just naturally has a powerset built for fighting Kryptonians. She depowered Zod's army.
I think it happened in.. War of the Supermen? Maybe? I don't remember.