Even many of 5* RGB lack of buff but ML 4* also need buff. They have potential to use but lack of EE and named in balance patch. Many of them are waste of character design and bad since day one.

Champion Zerato

S1 - Attacks two enemies including the target with an earthen blast, transferring two debuffs from the caster, and recovers Health proportional to max Health. Damage dealt increases proportional to the caster's Defense.

S2 - Immune to debuffs which prevent movement and decreased Hit Chance, unable to resist other debuffs. After being attacked, when the caster has a debuff, has a 100% chance to counterattack. Increases Effectiveness by 100% when the caster is debuffed

S3 - Attacks all enemies by slamming rocks and has a 85% chance each to inflict decreased Defense and decreased Attack for 2 turns. Grants increased Defense to the caster for 2 turns. Damage dealt increases proportional to the caster's Defense.

EE : +DEF%

S1 - Increases Combat Readiness by 15%

S1 - Increases damage dealt by 15%

S3 - Increases all of Cataclysms' effect chances by 15%.

*** unable to resist other debuffs = he can't resist(15%) any debuffs including seal and bind. Lower his ATK multiplier but add DEF multuplier. His damage will be lower but a lot more tanky. 

Peacemaker Furious

S1 - Swiftly attacks the enemy. When used on the caster's turn, grants an extra attack with the same skill if the caster is buffed. Damage dealt increases proportional to the caster's Defense.

S2 - Increases Speed and Defense of all allies for 2 turns, before granting an extra turn to the caster.

S3 - At the start of the battle, grants indomitable for 3 turn. Attacks all enemies with a huge explosion, decreasing Combat Readiness by 30%. Penetrates the target's Defense by 60%. Damage dealt increases proportional to the caster's Defense. Absorbs some of the damage dealt as Health.  Removes 10 Soul from the enemy.

Soulburn (S3) - Increase damage dealt

EE : +DEF%

S1 - Remove 3 souls

S3 - When an enemy is defeated, resets cooldown.

S3 - Inflicting up to 30% injuries

Great Chief Khawana

S1 - Cuts the enemy, with a 100% chance to restrict for 2 turn. 

S2 - Increases Critical Hit Chance by 30%. When someone triggers a Dual Attack, increases Attack of the caster by 25% and increase Combat Readiness of the caster by 15%. Increased Attack effect can stack up to 4 times.

S3 - With released power, dispels two debuffs from all allies and grants increased Speed and a barrier (proportional to the caster’s Attack) for 2 turns. Grants an extra turn. Grants Unity and extent buff duration of this skill to the caster for 1 turn.

Imprint : Effetiveness%  >  Dual Attack%

EE : +ATK%

S1 - Increases damage dealt by Vertical Cut by 20%

S1 - Absorbs some of the damage dealt as Health

S3 - Increases Attack of the caster for 2 turns

Celestial Mercedes

S1 - Attacks two targets with shock magic, with a 50% chance to make the enemy unhealable for 2 turns.

S2 - Attacks all enemies with a massive light sphere, Increases Attack of the caster for 2 turns and increases Combat Readiness by 20% according to the number of the target.

S3- Attacks all enemies by releasing spells of The Last Spellbook. dealing damage proportional to the enemy's loss Health. Decrease all skills cooldown for each enemy defeated by this skill.

Soulburn (S3) - Increase damage dealt

EE : +CRI%

S2 - Dimensional Rupture unable to be counter

S2 - Increase Hit Chance for 2 turns after using Dimensional Rupture

S2 - Instead of increases Attack, increases Critical Damage of the caster for 2 turns 

Angel of Light Angelica

S2 - Immune to debuffs which prevent movement, and after every attack suffered by an ally except for the caster, increases Combat Readiness of the caster by 8% each. When suffering an attack that targets all allies, has a 100% chance to activate Guardian Angel.

Guardian Angel: Dispels one debuff from all allies before granting skill nullifier once.

EE : DEF%

S2 - Additional increases Combat Readiness of the caster by 2%

S2 - When enemy activating extra attack that target the caster, dispel two debuffs from the caster and grants skill nullifier once. Can activate once every 3 turns. Guardian Angel: Dispels one debuff from all allies except the caster before granting skill nullifier once.

S2 - Grants barrier proportional to the caster's Defense after using Guardian Angel

Roaming Warrior Leo

S1 - Attacks the enemy with a slingshot, with a 85% chance to inflict Bomb for 2 turns.

S2 - Fires a shockbomb at the enemy, with a 100% chance to decrease Defense for 2 turns. Decreases skill cooldown of Go, Racoo! by 1 turn. At the end of the turn, detonates bombs inflicted on the enemy. If successfully detonates bombs with this skill, inflicts Burn to all enemies except the target for 2 turns.

S3 - Attacks all enemies with Racoo’s help, decreasing buff durations by 1 turn before a 100% chance each to inflict decreased Speed and a bomb for 2 turns. Grants skill nullifier once to the caster.

EE change

S1 - Increases Fire Slingshot's decrease Attack effect chance by 10%.

S3 - At the start of the battle, grants Stealth to the caster for 2 turns

Fighter Maya

S3 - Attacks the target with a powerful smash, and when the target’s Health is 30% or less, increases damage dealt by 300%. Damage dealt increases proportional to the caster’s Defense. When an enemy is defeated, inflicts extinction and grants an extra turn.

EE : +DEF%

S1 - Increases damage dealt by 20%

S2 - When get attacked, has 20% chance to counter attack

S3 - When the target’s Health is 30% or less, increase Hit chance and Critical Hit chance of this skill by 100%