FFI - Thief, yes he becomes a ninja later but that doesn't change the fact the Thief is a pretty crappy class on its own and mostly dead weight for most of the game.

FFII - Leila, not relevant to the story beyond giving the party a boat, she could have easily been just a simple boss like the pirate from FFI.

FFIII - Evoker, there is a very good reason why this class never shows up again...

FFIV - FuSoYa and Cid, though relevant to the story (the whole cast is actually) these two are pretty lousy party members. Tellah would be here too if it wasn't the fact he's crappy for story purposes.

FFV - Krile, I like Galuf better and as one member pointed out to me, she really is a little too perfect.

FFVI - I love all the cast but I would have to say Gau, Umaro, Mog, and Gogo because none of them are relevant to the plot.

To Levian: How dare you choose my fave character in VI

FFVII - Yuffie and Red XIII, once again , mostly irrelevant to the plot though I would add to the fact that Yuffie is excruciatingly annoying and Red XIII is actually a fairly boring character once the novelty of being a talking cat wears off.

FFVIII - Selphie and Quistis, Selphie is the obligatory "hyper active, sugar addict girl character" who is just as annoying as ever and never has much growth as a character. Quistis starts the plot relevant but once Squall becomes a SeeD she not only loses most of her relevance in the story, she also starts becoming retarded (don't think I don't remember the whole incident in Galbadia where you came damn near close to compromising the mission cause you hurt Rinoa's feelings) though I would argue most of the cast falls into this problem as most appear to play a minor role and then never grow as characters again except for Squall.

FFIX - Quina is a bit obvious, despite the fact I love her/him/it cause I do feel Quina is entertaining and fun. Amarant is kind of a non-entity fulfilling the role of "dark brooding badass" but he's mostly irrelevant. Garnet and Eiko, I have a problem with these two. Garnet is important as a plot device but the more I think about it the more I feel it would have worked better if she was only a temp character cause she's pretty much a sub-par character in the cast thanks to the story line screwing her out of most of her useful abilites and making Eiko the competent White Mage. On the other hand, we have Eiko who isn't really relevant to the plot as a character either (she's the token hyper active girl character) despite being fairly useful as a battle party member. I just feel we could have done better if we stuck to one and made the other a NPC.

FFX - Though it would be easy to say most of the cast, I will mostly say Kimarhi cause he's the glaring example of black sheep here. The other characters might have weak justifications but Kimarhi really has nothing. He never talks so he gets little character growth and despite his physical stature he's actually a terrible character in a game where niches are more important than versatility. Throw in the fact he's the worst Dragoon and Blue Mage in the series thanks to them being limited to his Limit Breaks and we have ourselves the most pointless character in the game if not the series.

FFXII - Obviously Vaan cause his plots resolved a few hours in and people mistake his role as "errand boy" for being the main character. He's a fine example of executive meddling. At least Penelo has a bit more usefulness cause of Larsa... Fran also falls in here cause she's basically Balthier's partner and nothing else. She gets an intriguing backstory that is sadly downplayed in the main narrative.

FFXIII - Hope and Fang, Hope is terribly annoying for most of the game til he gets one moment of awesomness in Chapter 7 then proceeds to be Mr. Positive for the rest of the game where he is equally annoying, he exists to add more angst to a story that is overflowing with angst. I feel the Director/Writer must have loved Hope the most cause not only does he get more screentime than most of the relevant cast, but he's actually the best party member forcing most people to use him. Fang is pretty much the most underdeveloped characters in the cast besides the villains. Besides being overprotective of Vanille and a hot babe, what else is there to her character?.... *crickets*.... exactly. She gets an 11th hour story scene during the ending but by then its too late. Fang is introduced far too late in the plot. I would also probably throw in Lightning as well cause she really doesn't develop much as a character. She's a total bitch for the first half of the game and Hope contaminates her and makes her little character growth turn into a mother hen, but beyond that she really doesn't do anything else for the plot. Part of this is because Lightning is basically the token "brooding badass" but seriously, despite Serah being her sister all her development as a character ends in Chapter 5/7 and then she proceeds to spend the rest of the game acting out as leader occasionally just to tell the player she's still there.