Yuffie comes from a long line of Ninja and has also given herself the title of 'Materia Hunter'. She enters the group when she loses a fight to you but is always on the look out for opportunities to steal your materia.
The main advantage of Yuffie is her ability to steal from and moph enemies. Also, like Barrett, she can attack at long range. Her ultimate weapon is the Conformer, which gets a boost depending on the strength of the enemy you're fighting. Her last limit break is All Creation..