As the level starts, Doge Darks will spawn. Gabriels will spawn after you when you attack the base. The Doge Dark spawn rate will increase for a while, when the Doge Dark spawn rate reverts to the beginning, and Gabriels will just stop spawning. These doges are extremely strong, so watch out. As the base gets damaged enough, a 150% Gentleman Bros. will come out with a Le'noir. Later, a second Le'noir will spawn.
Start off with some Eraser to stall the Doge Darks. Don't let them hit your base too much; they deal 16,000 damage per attack.
Summon Catdam, Ururun, and any Ubers you may have. Stack Jamiera, Crazed Titan, and King Dragon.
When you hit the base, Gentleman Bros and Le'noir will spawn. The Le'noir is the main damager, and Gentleman Bros is support. A second Le'noir spawns later.
Catdam outranges the Gentleman Bros, so he's very useful for slow damage. Also drop Awakened Bahamut occasionally, he can deal tons of damage.
The battle becomes much easier when you take out the Le'noir. Be patient and you should eventually win.