In the past FF main games, from VII to XII, there has been at least one character that is pretty much useless that people just doesn't use that much.
1)FF VII: Cat Saith, Yuffie. well never took them into any serious battle
2)FF VIII: Zell. I know some people will say Selphie or Quistis, but they both had extraordinary limit breaks that were really usefull for me
3)FF IX:Quina Quen. I didn't even bother to level her up and I normally have all my players to the same level expect for the lead characther that cannot be taken off the group
4)FF X: Kimary. I always wonder why he didn't have his own grid path, but I did spend my time to complete the whole grid with him
5)FF XII: Penelo, story wise she was useless, but combat not really because in FF XII you could pretty much made anyone looks strong and all my characters were pretty strong, reached level 94 with all of them.
So for the people who had played FF XIII, is there a useless characther among the group?
