Yuna is forced to switch to the Songstress dressphere and use Darkness Dance the whole battle. While Leblanc has Darkness on her, she will almost never hit with physical attacks. She can still use Thunder, which is fairly strong.
Leblanc is joined by Logos and Ormi. It's good to still have a Songstress, because Darkness still affects them all. The other two party members should focus their attacks on Leblanc while the Songstress dances. Leblanc should be taken down first, because her attacks can hit the entire party.
This is the final time the Gullwings have to fight Leblanc. She is stronger since the last time and is with Logos and Ormi. If all three members are alive, they may use the No Love Lost combo, which deals heavy physical damage and ignores defense. The first part of No Love Lost damages random characters eight times with each hit having a damage constant of 5, resulting in each hit having a base damage value of 21~24 HP; the second part deals 94~106 damage to all characters; and the final part damages one character by 3/8 of their remaining HP. Leblanc can also throw Flash Bombs and Hush Grenades at the party, which deal 46~52 damage and have a 50% chance of inflicting Darkness and Silence, respectively. If she has 14 MP or less remaining, she will use Osmose.
Leblanc operates on an action number device. If all three members are alive, and Leblanc's [8x - 5] turn has passed, No Love Lost is used. After her 25th turn plus the number of times No Love Lost has been used, she uses Not-So-Mighty Guard.
The party should to take down Logos first, since he has the least amount of health and Russian Roulette, which can inflict any status ailment. The player can use Grenades (preferably not Budget Grenades), which can do 281~317 damage to each member of the syndicate, which is about 1/4 of Leblanc's max HP. It is better to use them quickly, because Leblanc will use Not-So-Mighty Guard, which reduces the damage done from physical and magical attacks.
Another strategy involves using captured fiends. Using a captured Kukulcan is ideal due to its Heaven's Cataract move, which can not only do extreme damage to Leblanc, Ormi, and Logos if all three of them are in front of the Kukulcan itself (especially if the Kukulcan is at least Level 20), but also reduce their stats. The Kukulcan also naturally comes with Ailment Def., which blocks any negative status effects Logos can inflict with his Russian Roulette attack, including Eject. A captured Haizhe is also useful, as it can use Distortion Wave to cancel out any protective statuses Leblanc inflicts on her party with Not-So-Mighty Guard. If the player has a Chocobo in their party that is at least Level 40 and has learned Meteor, it can use Meteor to quickly end the battle.
Turn 1 Use Normal Attack on random character Turn 2 Repeat Turn 1 Turn 3 Repeat Turn 1 Turn 4 If (Has less than 8 MP remaining) Repeat Turn 1 Else Use Thunder on random character Repeat from Turn 1
Turn 1 Use Normal Attack on random character Turn 2 Use Sonic Fan Turn 3 If (Logos and/or Ormi have HP) Use Love Tap on Logos or Ormi Else Repeat Turn 1 Repeat from Turn 1
Basic Pattern: Turn 1 Use Not-So-Mighty Guard Turn 2 Use Normal Attack on random character Turn 3 Does she have 14 MP or less remaining? Yes - Use Osmose No - Use Fira on random character (1/4 chance) Use Blizzara on random character (1/4 chance) Use Thundara on random character (1/4 chance) Use Watera on random character (1/4 chance) Turn 4A (1/2 chance) If (Ormi has HP remaining) Use Love Tap on Ormi Else Use White Wind Turn 4B (1/2 chance) If (Logos has HP remaining) Use Love Tap on Logos Else Use White Wind Turn 5 Repeat Turn 1 Turn 6 Use Mach Fan (3/5 chance) Use Flash Bomb (1/5 chance) Use Hush Grenade (1/5 chance) Repeat from Turn 2 Action Number Pattern: After her [8x - 5] turn (3rd, 11th, 19th, etc.), and both Ormi and Logos have HP remaining, No Love Lost. After her [25 + times No Love Lost was used] turn, Not-So-Mighty Guard