That's true, even if you had stronger fighters and the elemental advantage, it's still really hard to fight her, especially on rift battles, where the AI is a lot better than in any other mode, i once fought with Gray Matter (1,700 at the moment) against Just Kitten (1,020 or so), lost without even landing a full combo because she blocked all my blockbusters, it's her SA i know, but still, that'd give her the chance to pull out a 40 combo without even giving me a chance to counter or block, it was so frustrating that i just used Windswept (3,700) to finish her off, even then she somehow managed to get a lot of my health off, after that i didn't even try winning that battle since the guy had like 7 Ms Fortunes, two in the boss node.
I do find fights against Squigly and painwheel to be hard too, however, they have some strategies which you can use to win against them, but it's different with Ms Fortune since it seems to me she doesn't leave any kind of opening, either when attacking of defending.
I do like the fact that she can pull off incredibly long combos when having basic, head, special and BB as different ways of attacking, however hey should at least nerf her in some way, at least lower her base attack or crit chance, head hits could have a chance of stunning you for 1 second, or even better, make it so that you can only use certain attacks when using Head Games, it might not make a lot of sense, but i think it'd be a decent way of balancing the fights.