Again, Carlie's physicals are half average offence. Thunder Sabre will increase that, but not to even average, and now she's getting 2HKOed (no Black Curse), which makes a victory via sleep an easy thing to pull off.
Anyway, crunched some numbers. Assuming Black Curse adds 80 to all of Carlie's damage (I think that's what it should do, looking at the stat topic), and takes 33% off both Demi's Strength AND Attack, and assuming a SD3 turn is 2 seconds, and assuming Black Curse is viable...
With Dark Sabre cast, Carlie needs 4 turns to kill Demi. Regular physicals are 6HKO, killer turn with her L3 is low 2HKO. Demi needs 3 turns to kill Carlie. Two of those need to be Phonons.
Here's Demi's strategy. Hit Carlie once. Carlie won't heal now because even if you let her heal and attack on the same turn she'll run out of resources waaay too fast since she only makes Demi heal once every 3 turns and their MP pools aren't that different, as discussed. Demi is now two turns from victory. When she gets her chance, she uses sleep. She has enough uses of sleep that, sooner or later, it WILL cause Carlie to lose 2 turns (note that since Demi is faster, it always makes Carlie lose 1 if it hits). Two Phonons and it's over.
Needless to say the fight is laughable if Black Curse does not work. To give you an idea of the scope of the failure, Carlie now needs 6 turns to kill Demi, while as mentioned, it's 2 in the other direction.
Don't think I'm missing anything, so vote confirmed.
Loose ends: After Barrier, Carlie 4HKOs with magic, same as with physicals... this just burns through her MP faster.
Also, OK commented he sees Carlie with 2x average damage. I can't think of an average that gets her that high. The best I can see for her is the following: everybody gets one attack, regardless of recharge time (classic view says the fighters get in two swings per "turn"). I'll additionally throw out Deathspell entirely since IIRC OK doesn't allow it for some reason, and will assume the L3s take too long to cast, sticking Angela with Dark Force.
Angela: 431
Carlie: 381
Lise: 353
Hawk: 296
Kevin: 186
Duran: 95
Average: 289 (Disclaimer for people not reading closely: I DO NOT RECOMMEND THIS CURVE FOR GENERAL USE)
Not especially close to 2x, really. Note that this average additionally is a one-turn one and does not account for backended damage via techs or stat mods. Note also that, if you use this interp, then Carlie and Angela should logically be very, very slow... after all, the fighters get two attacks in before they get off one spell, and Hawk/Lise's spells have almost as large a speed advantage. Still, humouring this idea and assuming all speeds are equal and Kevin fails at offence... Carlie now 3HKOs post-Barrier with Ghost. 2HKOs if she tries to keep Black Curse in place, but again, she just can't win that way, as Demi just heals until Carlie is out of MP. If both are 3HKOing, I still think Sleep will tilt it, though it's closer now. Although if you've thrown charge speed out then you probably shouldn't give Carlie credit for super-fast Heal Light and she's screwed again. Sooo yeah.
Funny, the more I look at this match the less close it gets.