Yuffie is yet another mysterious figure in this game. She is an optinal character, and can be useful at times. She originates in Wutai, a town in which materia in scarce. She tricky, and will steal your materia when you're not looking--just to make her father proud. If you go to Wutai, you'll have to save her and help the Turks, just to get your materia back. But it's not as easy as it seems, there's also a tough boss here, at least at level 20. There's more about that in the Yuffie bonus section.
Yuffie is just like Tifa--not very strong in HP. Her MP is just about the same as Tifa's, too. I switch between her and Cid most of the time--Yuffie can be quite useful. She has good accuracy, just a little less than Tifa, and her attacks with her ultimate weapon aren't bad; about 3400 most of the time, 7500 other times.
Getting Yuffie
Yuffie's Weapons