Magoichi Saika in Sengoku Basara 3 has it all: good speed, really good attack, great range, and she only gets better when you equip her with certain items. She's so good that my friend, who never plays crowd-control games, was able to get through the whole thing with a barely powered-up Saika on the hardest difficulty with no trouble.

I'd throw Kanbei Kuroda in there too (from the same game as Saika), but only if you can master his roll cancel. You master that and learn the timing of his Final Atomic Buster-like super art to get all the throws out of it, there's no way you'll have any trouble beating his story mode. Do his regular combo, then the wrecking ball swing move, cancel into the shockwave, roll as the shockwave finishes animation, and do it all over again and you'll pretty much steamroll over everything. The bosses die quickly to the Final Atomic Buster, usually within only two uses of it.

Nicole from Guardian Heroes was a healer, but a really kick-ass one. Not only did she have awesome healing spells, she had some really fast attacks and the barrier of doom. With the barrier you could trap bosses in the corner of the stage and make them bounce off the barrier until they died and protect yourself from attacks too. The only bad thing about it was that you didn't gain experience for hitting them with the barrier or even killing them with it.

Even though Blue Dragon is quite easy, I seem to remember having Marumaro as a Monk and decimating a lot of monsters by himself (he had the Chakra ability, he had a move which hit every monster in the other party, and some other really crazy things). Just scary. Having Jiro with healing spells and Shu and Kluke whacking away made the game probably the easiest RPG I've ever played.