Hope – Synergist Crystarium

Character Hope
Role Synergist
Hope, like Sazh, eventually gets almost every basic Synergist Ability (though he gains Veil over Sazh's Vigilance). Until Chapter 10, however, Hope is primarily a defensive Synergist, with Abilities like Protect, Shell, and Bar-spells. Which of the two is more useful depends largely on how hard the enemy in question hits.
Compare Hope – Synergist Crystarium to other Crystariums

Related

Hope

Eidolon Alexander (Chapter 11)
Base HP 170
Maximum HP 18,000
Base Strength 8
Maximum Strength 1,100
Base Magic 20
Maximum Magic 1,900
Starting Weapon Airwing
Primary Roles Ravager, Synergist, Medic
Accessory Crystal Synergist 3
Accessory Crystal Medic 8
Accessory Crystal Ravager 10
ATB Level Crystal Synergist 8
Chapter 1

Fang – Synergist Crystarium

Character Fang
Role Synergist
Fang is an interesting Synergist that can be quite effective despite having less Abilities than any other Character. She has access to Veil and Haste, but more importantly she gets the high-powered Abilities Bravera, Faithra, Protectra, and Shellra. These Abilities, exclusive to Fang and Vanille, are more powerful versions of the Abilities they are based on, but have a much shorter duration. You'll have to pay a lot more attention to your buffs if you use them, but the payoff can certainly be worth it.

Hope – Commando Crystarium

Character Hope
Role Commando
Hope's biggest disadvantage as a Commando is his low strength stat, but then, he gets Ruin right away so that shouldn't be a big issue. In fact, Commando can be very effective for Hope against enemies that are weak against Magic but resist most Elements. He lacks many auto Abilities, notably including Launch, making him a poor choice as your lone Commando, but then, you're not likely to use him in that Role.

Hope – Medic Crystarium

Character Hope
Role Medic
Hope has access to every Medic Ability, which combined with his high Magic stat makes him the best Medic in the game. He is one of only two Characters (along with Vanille) with access to Curaja, a vital Ability when dealing with powerful multi-target attacks from the game's tougher foes.

Hope – Ravager Crystarium

Character Hope
Role Ravager
Hope is the best Ravager in the game, provided your target is not more vulnerable to Physical than Magic attacks. The only Abilities Hope lacks are the -strike Abilities, which is usually fine but will occasionally make him virtually useless. Hope also has the Last Resort special Ability, which will very rapidly build the chain bonus of a staggered target.

Hope – Saboteur Crystarium

Character Hope
Role Saboteur
Like Sazh, Hope is one of two Characters that can inflict every Status Ailment in the game. However, Hope exclusively gets multi-target versions of these debuffs (as well as the standard Dispel). This makes Hope an effective Saboteur against groups, but since his Abilities cost three times as many ATB segments, he's a liability when you're only looking to debuff a single target (which is usually the case). He can't even use two debuffs in a round without the Nue.

Hope – Sentinel Crystarium

Character Hope
Role Sentinel
Despite having the lowest HP in the game, Hope makes for a fairly interesting Sentinel. Like Lightning, he doesn't get Challenge and favors Elude over Mediguard and Steelguard, but Hope also gets the counterattack Abilities, Entrench and Vendetta. He's fun to play around with, but not much use against truly powerful enemies.

Lightning – Synergist Crystarium

Character Lightning
Role Synergist
Lightning is a surprisingly effective Synergist, gaining all of the basic Abilities with the exception of Bar-spells. Her biggest failing is not learning Haste or Vigilance until Crystarium stage 10, however. Once all is said and done, she's quite effective simply because Bar-spells aren't of much use against the toughest enemies anyway. Too bad there's no Barstone in this game.

Sazh – Synergist Crystarium

Character Sazh
Role Synergist
It takes him a while to get there, but Sazh is the most complete Synergist in the game. He and Hope have very nearly the same set of Abilities, though Sazh gets Vigilance instead of Veil. However, Sazh will first gain access to offensive buffs like Bravery, Faith, and En-spells, making him the offensive Synergist for the first nine chapters of the game.

Snow – Synergist Crystarium

Character Snow
Role Synergist
Snow is a decent Synergist as long as you don't care about elemental buffs—he doesn't get any Bar-spells or En-spells, nor does he get Veil. He does have the standard Protect/Shell and Bravery/Faith pairs, though, so he's a useful enough Synergist in a pinch.

Vanille – Synergist Crystarium

Character Vanille
Role Synergist
Along with Fang, Vanille is one of two Characters that has access to Bravera, Faithra, Protectra, and Shellra, high-powered Abilities that have a short duration to balance their extra effectiveness. Unlike Fang, Vanille has a decent number of standard Synergist Abilities as well, including Veil, Vigilance, and the Bar-spells. She is the only Character in the game that doesn't get Haste, however, so she's not very effective as your only Synergist.

Synergist

Bonus Type Extended Enhancements

Synergist

Abbreviation SYN
Role Bonus Extended Enhancements
Base Bonus (Self) None
Role Level I Bonus (Self) Duration Bonus: +15%
Role Level II Bonus (Self) Duration Bonus: +30%
Base Bonus (Allies) Duration Bonus: +5%
Role Level II Bonus (Allies) Duration Bonus: +8%
Role Accessory Supporter's Amethyst (Grants Duration Bonus: +20% to self)