Erza:
A 10 	80% boost to all parameters
B 10 	30% boost to Def, max HP
C 10 	150% boost to Spark damage
D 10 	Raises Atk parameter limits to 150000
E 40 	Probable resistance against 2 KO attacks
F 15 	10% damage reduction
G 35 	Enhances BB's Taunt duration and Def boost effect
H 35 	Adds 50% damage reduction for 2 turns effect to BB/SBB

General use: A B C D F G H (120 SP)
Colo: E F G H (125 SP)

Zeref:
A 10 	100% boost to Atk, max HP
B 10 	150% boost to Spark Damage
C 15 	Enormously boosts elemental damage [200%]
D 25 	Enhances LS's raises Atk parameter limit effect [+30000]
E 35 	Adds probability [15%] of activating BB/SBB/UBB twice for 2 turns effect to SBB
F 10 	Enhances SBB's probability of activating BB/SBB/UBB twice effect [+10% chance]
G 35 	Adds 26 combo powerful Dark attack [200%-900%] on single foe (damage relative to remaining HP) to SBB

Recaster build: A B C E F G (115 SP)
GR leader build: A B C D G (95 SP)

Gray:
A 10 	80% boost to all parameters
B 10 	150% boost to Spark damage
C 20 	Enormously boosts elemental damage [200%]
D 10 	Damage taken boosts BB Gauge [2-3BC]
I 30 	Adds considerable Atk, Def, Rec boost [140%] of Water types for 3 turns effect to BB/SBB
J 25 	Adds probable [15%] evasion for 2 turns effect to BB/SBB

Total SP: 105

Achnologia:
A 10 	90% boost to Atk, max HP
B 10 	Boosts Atk, Def [70%] when BB gauge is above 50%
C 10 	150% boost to Spark damage
D 15 	Raises Atk parameter limits to 200000
E 40 	Adds 27 combo powerful Dark attack [650%] on all foes to SBB
F 25 	Adds considerable Spark damage boost [100%] for Dark types for 3 turns effect to SBB
G 25 	Adds probable [20%] evasion for 2 turns effect to BB/SBB
H 30 	Adds Spark damage considerably boosts BB gauge for 3 turns effect to BB/SBB [3-4 BC]
I 25 	Adds max HP boost effect to SBB [30%] / UBB [50%]

Mono dark: A C D E F G (Total SP: 125). G can be swapped out for H if you lack a unit with BC on spark. Can also be swapped for I for more stats. If you can't OE+3, skip F or G.
Other build: A C D E. From here is what you want it to cover.