I've found that they jump around like crazy, and do all this random shit that is able to go right through my swords. Air dashes, random things with the staff, even just doing special moves allow her to go right through the swords, and she's to fast to do anything productive with C (all of them), and out of range to do anything with A most of the time. I'm stumped at this match up really.
Edit: Most Litchi's I've faced love to jump around, just Jump with them (full screen to 3/4th Screen) and Air Sword them (either neutral or down sword) It seemed to work against the CPU on Hell mode, so it might work on a lot of your opponents.