Thanos (Endgame) vs Collection of MCU villains
Instead of the heroes having to stop Thanos, it's a collection of MCU villains that have to stop him. Some are not truly villains to the core perhaps, but did have a villainous agenda.
Ultron
Loki in the Destroyer Armor (Thor)
Abomination
Iron Monger
The Mandarin (Shang-Chi)
Namor
Ikaris
Can they win?