KATO
Element: Fire
Standard Weapon: Dual Swords
Fighting Style: Slice'n'Dice, Flaming Swords
Strenghts: high damage, attacks are performed faster in Offensive Stance
Weaknesses: long recover after hit, no defending
Kato is a specialist in dealing damage with field-covering fire attacks. Mostly, he combines fire moves with his swordmanship, even being able to charge his swords with pure fire energy.
Instead of simply throwing shuriken, as most ninjas would, Kato has learned his basic attack style from Onimaru: Wielding two swords and slicing up everything that comes too close.
Another special fact about him: He is using a draw-fighting style, storing energy in his sheated sword and then releasing it after the draw. Therefore pressing D won't lead him to defending frames, but to an Offensive Stance. All moves done from this stance will consume less mp and will be performed slightly quicker.
SUIKAN
Element: Water
Standard Weapon: Dai Shuriken
Fighting Style: Water & Ice Nin-Jutsu
Strenghts: has 550 mp as maximum, higher mp regen
Weaknesses: only minor direct attack capability, no melee attacks
Suikan's main weapons, the Dai Shuriken, are bigger, quite devasting shuriken, knocking over most enemies in a single hit.
Suikan usually prefers to stop foes with these weapons and then use some of his powerful Nin-Jutsu abilitys to bring the pain. Alternatively, he can use same abilities to heal and aid his allies.
On the downside, Suikan lacks any sort of melee combat, making him an easy target on close range.
FUSEJ
Element: Wind
Standard Weapon: Shuriken
Fighting Style: Advanced Slice'n'Dice, Cutting Wind Style
Strenghts: high speed, powerful jumps & dashes, can dodge after and before being hit
Weaknesses: overall low damage on basic attacks and abilities, takes longer to recover from hits
After years of mysterious training, Fusej obtained perfection in the use of shuriken and swords. Additional, his speed is far superior then anyone else's known.
But though his attacks being fast, they are lacking in strength and, in terms of damage, cannot come close to Kato's slow, yet mighty strikes.
Fusej can as well utilize a vast amount of wind-based abilities, cleaving through piles of enemies, if necessary.
Last but not least, Fusej can use his superior speed to dodge anything thrown at him. Pressing D after being hit (or right before being hit), will consume some mp and will cause Fusej to dodge upwards.
If in danger of being hit again, you can hit A to perform a quick backwards dash after the initial dodge. Lastly, you can add J to teleport to an ally after said second dodge.
DOKUM
Element: Earth
Standard Weapon: Fists
Fighting Style: Master of the not-drunken Fist, Roll'n'Rock
Strenghts: high strength for melee and throwing, extraordinary defense capabilitys, heals by casting moves
Weaknesses: slower then other ninjas, only has 450 mp, lower mp regen, cannot jump
Dokum never leant to utilize weapons properly and whilst Kato handed him a reserve sword, Dokum is rarely seen using it. But given Dokum's innate strength, he really doesn't need more then his fists as weapons:
Whilst his strikes are slow and he lacks the jumping abilities of other ninja, his powerful attacks easyly daze opponents. And whenever he sees the opportunity, he will grab a dazed opponent and (literally) smash him into the ground.
Additionally, his defense is superior to anything else and he can easyly hide behind his block, waiting for the right moment to conter with aimed blows of himself.
Of course Dokum does not only rely on these direct fighting abilties, but as well has a useful kit of moves to support his frontal approach.
The character Dokum was reworked in version 1.22 and any screenshots or moves described in this thread may not be accurate anymore.