Gilgamesh

Gilgamesh is a one time encounter as the level boss of Mission 6.

Strategy

This fight is scripted as long as players will follow the sequence correctly and does not fall down at all. Refer to Best Segmented Times for the good cycle.
You stay at the air as much as possible while avoiding Gilgamesh spike with Air Taunt or Roulette Spins
Vergil trivializes this with Beo's Hell on Earth and Heavy Rain Blades however, he has to avoid forcing Gilgamesh to body press while building for SDT and Concentration meter with Rising Star → Trick Down loop.
Nero must successfully detonate Overture or the fight will be slowed down by significant amount. After that, it's Exceed + Battery spam.
NG+ Nero can end the fight with one knock down due to Gerbera and Ragtime.
Special Edition may affect his behaviour differently due to turbo feature.