Oh, well I see a lot of ninjas in general. But Kasumi is the most mashable lol =P don't really need to be too familiar with her to get in some hits. Same with Hitomi. Ayane, not so much. I don't view Ayane as a pick up and play character.
Well, online is a very different thing from offline. For example, online, a Christie player can literally get away with mashing PPPPPPPPPPPPPPPPPPP with the occasional PPPP2P and WIN over an experienced player, simply because the string becomes a natural combo on block and is perfectly safe online. Online, Christie IS the noob's ticket to victory. Offline, that shit will never, ever work.
Well, yeah. Christie is brutal. But offline you actually have to do stuff other than PPPPP. I'm not kidding when I say that those two strings are literally all you need online. You can see it coming from a mile away (and you will, since they're predictable as hell), but you are powerless to do anything.