Wow, it has been a really long time since I did one of these.
Dean: Dean spends the first part of the game as a stupid, incredibly annoying doofus who is absolutely obsessed with Golems (these big stone-ish ancient robot things). It's like listening to Jude from Wild Arms 4 all over again, only instead of the never-ceasing topic of babble being All Adults Are EVIL, it's Holy Fuckballs Guys I Just Saw A Rusted Screw That Could Potentially Have Once Been In A Golem And I Have Now Crapped My Drawers Out Of Excitement.
Thankfully, Dean gets more tolerable after a little while, once he starts losing interest in Golems. He is sadly just as stupid as ever, but considerably less annoying. Of course, he transforms into a generic stupid protagonist at this point, so his character loses what little separated him from the sea of other do-gooding simpletons, but honestly, I was so relieved to see him not creaming his pants at the mere thought of moving stone statues that it's a trade I'm willing to make.
Oh, and I've mentioned this before, but his weapons are one of the stupidest in gaming history. Instead of just using the guns to shoot enemies like he shoots things OUTSIDE of battle, he swings the long, unwieldy blade things on their handles into enemies, even though shooting a bad guy in the face at point-blank range would be WAY more damaging, faster, and easier to do. God Dean is an idiot. He should've just kept the shovel he used as a weapon earlier in the game; at least he used THAT tool more or less as well as it could be.
Rebecca: Rebecca's entire character development is about romantic feelings that she never acts on or gets any kind of closure for.
Avril: Wow, a magical girl of mysterious plot-important origins who has amnesia. What novelty!
Greg: Greg is an archeological terrorist. Yes, that means exactly what you think it does--he's an extremist who blows up artifacts and relics (Golems, in this case) for the purpose of getting attention of the upper class that's wronged him (in this case, one certain upper-class asshole), so as to draw his enemy out so Greg can have revenge (a plan which, incidentally, barely makes any sense at all and doesn't work).
This game wants you to think that this makes Greg deep and cool. But we don't all get what we want.
Chuck: Why is Chuck even here? I don't remember a single damn time where having him in the party significantly contributed to the plot or the heroes' efforts. Hell, he made more of an impact as an NPC, before joining you.
Carol: Okay, I know I recently ranted about how weird it is that RPG parties are okay with letting children encounter life-threatening danger regularly. But seriously, who the hell thought it was okay for a 12-year-old to run around with BALLISTIC MISSILES strapped to her BACK?
Volsung: A misunderstood mama's boy caught between two racial worlds whose hardships in life because of his heritage make him bitter and genocidal. Gee, you think maybe, just maybe, someone on the Wild Arms 5 development team played Final Fantasy 10?
Monowheel: Yeah, okay, not a character and not the main villain. But so stupid it needs to be mentioned. You know that old, old rant I did on Xenosaga 2's KOSMOS's space motorcycle? As nonsensical and stupid as that vehicle was, it's a fucking Rolls Royce compared to this thing. The Monowheel has to be the most undignified transport of all time, bar none. I've seen it all--space motorcycles, large golden chickens, seagulls capable of carrying a fully grown human's weight while flying, talking dragon sailboats, cowardly mine-cart-pulling turtles, and just loading yourself into a cannon and being shot into foreign countries. But the Monowheel is the most idiotic, lame form of transportation I've seen in an RPG. And the worst part is, once you see how awkward, lethargic, and annoying the controls for Asgard (your second vehicle in this game) are, you'll actually want to suffer the indignity of the Monowheel as often as possible when traveling rather than fumble around with Asgard's crappy movements.
No, wait. I forgot. The worst part of the Monowheel is when Dean actually attempts to use it as a melee weapon at the end of the game. Oh, you WISH I was kidding: http://www.youtube.com/watch?v=4RuVegUqieM (scene really begins at about 1:02 if you're in a hurry). If I ever make a list of the Top 10 Stupidest Moments in the History of RPGs, I am 99% sure that this scene will be there.