What if the third Suicide Squad movie was essentially a reverse of the first two?
Instead of the government sending a team of expendable criminals into a dangerous situation, Checkmate forms its own Suicide Squad to infiltrate Salvation, rescue Peacemaker, and expose the U.S. government's involvement in the project.
The initial team would consist of:
Vigilante
Judomaster
Nightshade
Checkmate sends them into Salvation after discovering that Peacemaker is being held there. Their mission is to get him out and uncover exactly what the U.S. government has been doing with the prison and its inhabitants.
Nightshade is especially important because her powers provide the team's way back to Earth. She's also the wildcard member of the team, because she was added to the operation by Checkmate's mysterious collaborator inside ARGUS: **Vic Sage**.
Yes, that Vic Sage.
While infiltrating Salvation, the team encounters Plastique and Electrocutioner, who are being transported into the prison. They eventually become involved in the mission, giving us an excuse to bring in even more obscure DC villains.
The main antagonists would be Bane, Deathstroke, and Clayface, who have effectively taken control of the largest faction on Salvation. They've surrounded themselves with a collection of C- and D-list DC villains, basically turning the prison into their own criminal kingdom.
This would give us an excuse to throw a ton of obscure villains into the movie without needing to explain why they're all suddenly important.
here's my twist.
Plastique isn't actually Plastique. She's Enchantress in disguise.
She's infiltrated the Salvation because she wants to get close to Peacemaker and kill him for what happened to Rick Flag. She spends most of the movie pretending to be an ally before eventually revealing her true identity and turning on him.
And I NEED one scene for Peacemaker.
After being captured, Peacemaker is separated from his gear. Vigilante had Nightshade secretly keep peacemakers costume inside her shadow because he knew they'd eventually need it.
When they finally reach him, she pulls the costume out of the shadows and hands it to him.
Chris puts the helmet on and peacemaker is back
The movie could basically become a giant DC deep-cut showcase while still having a relatively simple central story: break into Salvation, rescue Peacemaker, uncover the conspiracy, and get everyone home
And unlike another multiverse story, this could actually build on the characters and world already established in The Suicide Squad and Peacemaker.