Most useless character in the series?

[Wolf Kanno]

That's really the point though - he takes way too much effort to just be an inferior copy of anyone on the team.

Nah, he just becomes that if you *don't* put the effort in =P

You can say that about most "useless" characters though. Kimarhi has no real strengths beyond starting right on top of the Ultima spell and his stats don't mesh as well as other characters. Rikku will always be faster than him and her Mix command is infinitely more useful than Ronso Rage, allowing her to be a thief, white mage, and black mage without even touching Yuna or Lulu's sphere grids. By the time Auron joins your team, there is no real reason to use him besides leveling him for the obnoxious solo boss battle he gets. The way combat works never really gives him much purpose beyond being a poor substitute for Auron and Rikku and once you get them, he's next to useless for the main game as he's stuck always playing catch up to all of the more specialized party members. You can make him a decent fighter but in that same time frame, you can make the rest of the cast even better than him.