Tidus: The game's main character. He realizes the situation around him and has tremendous courage. Not the most balanced character in the game, but probably more balanced than others. A little more agile than Kimahri, yet weaker than Auron, and doesn't even come close to having the magic powers of Yuna. He's not really a fighter, but a strategist. He won't impress you with his stats, but you'll be impressed by how much he can mean to the party's victory.
Overdrive: Swordplay ~ Has a unique Overdrive. A meter will run once the Overdrive starts and if "X" button is pressed at the time when the gauge hits the middle bar, he will deal extra damage. However, for every unsuccessful try the damage done is weakened by a point statistically. You can gain the next Overdrive as you perform them in succession. Ultimate Overdrive: Blitz Ace; hits all opponents, must use previous Overdrives 80 times to acquire.

Yuna: A summoner who is determined to defeat Sin. Yuna's magic is almost double of that of Lulu's...so teaching her Fire and Blizzard early on can do as much damage as Lulu's Fira or Blizzara. Raising the stats of Yuna is critical to the success of her summons as the stats of her summons rise concurrent with Yuna's stats. Although Yuna's strength may be very weak, her summons can deal out tremendous physical damage ranging from 5000 to 9999.
Overdrive: Grand Summon ~ When in Overdrive mode she can summon any one of her Aeons and that Aeon will automatically be in Overdrive mode. However, once she uses that Overdrive for that certain Aeon,the Aeon's previous Overdrive goes back to it's original state, which means that she can cast two consecutive Oblivions!

Wakka: A longtime Blitzball veteran, and Yuna's guardian, Wakka can sometimes be a little blind when it comes to common sense and his faith in Yevon. He is obviously a very religious individual and by far not the most powerful of attackers, and by far not the weakest of attackers either. His stats are average, His stats are average, but his special abilities to inflict Silence, and Dark status early on is invaluable. His Blitzball is the most accurate weapon in the game.
Overdrive: Slots ~ You must win Blitzball tournaments and league games to acquire his other Overdrives. He almost always hits flying enemies with his Blitzball. Whenever you see a flying creature, only have Wakka attack it.

Lulu: Guardian of Yuna and master of black magic. She's not very emotional and is good at hiding her feelings, but she is a strong willed character that has a lot of sense of things around her.
Overdrive: Fury ~ Her Overdrive consists of casting multiple magic spells against an opponent without expending any MP and Reflect or Shell status will not protect against this Overdrive. She can use this even when she is silenced. You will have to rotate the RIGHT analog stick clockwise several times to determine how many times she will cast a certain spell.
Overdrive spells : Fire, Water, Thunder, Blizzard, Fira, Watera, Thundara, Blizzara, Firaga, Wateraga, Thundaga, Blizzaga, Bio, Demi, Death, Drain, Osmose, Flare, Ultima.

Auron: You first meet him in the beginning of the game. He's a rather cloaked person with a matching personality. His fighting skills however are not a mystery. He's a very capable player to carry the load and definitely reliable in most boss battles.
Overdrive: Bushido ~ Auron's Overdrives require quick button motions and such to perform. To advance his Overdrive status you must collect Jecht Spheres, Auron Sphere, and Braska's Sphere. His deadliest is Tornado which hits all opponents and requires ALL 10 spheres; You won't get his first Sphere until somewhat late in the game and the 10th sphere needed to complete his ultimate overdrive is Braska's Sphere - at Mt.Gagazet in the Mountain Trial area.

Kimahri: Not big on words, but makes up for it on the battle field. His Lancet ability allows him to drain MP and HP from his opponents. This is a very useful attack early on, but as you can expect, it doesn't do much damage.
Overdrive: Ronso Rage ~ Kimahri's Overdrive consists of learning attacks from opponents using the Lancet ability on them. However, Kimahri doesn't have many attacks on his Overdrive so you won't get a new ability each time you use the Lancet attack.
The following consist of Kimahri's abilities: Jump, Fire Breath, Seed Cannon, Self-Destruct, Aqua Breath, Doom, White Wind, Stone Breath, Nova, Bad Breath & Mighty Guard.

Rikku: Pretty much another Yuffie of FF7 fame or Selphie of FF8 fame, but she has a better handle on situations and is a little more emotional than her FF counterparts. She isn't much of a fighter and her biggest strength doesn't lie within her abilities, rather the items that you can acquire with her. She can steal rare items and bribe opponents.
Overdrive: Mix ~ Her Overdrive chart is enormous. When you have the Overdrive started you will be prompted to select two items to mix. You can mix any two items in your inventory (except for equipment) and you can mix two of the same item for possibly double the effect to get various results. It's usefulness depends on what items you mix, and more importantly, what items you had to begin with.