Ideally, a Teen Titans movie would coincide with Batman films featuring Dick Grayson, which would make Teen Titans a spin off of Batman.
Robin, Cyborg, Beast Boy, Raven, Starfire should be the team. Setting up sidekicks without movies for Aquaman, Flash, and Wonder Woman would be tough, so that should eb the team.
First film should be against Deathstroke, maybe show Terra's betrayal in that one. The second should be about Brother Blood, and at this point Robin should become Nightwing (show the transition in the Batman films) Nightwing and Starfire should be in a relationship at this point too.
Third film would be full out apocalypse with Trigon as the main villain. Deathstroke would ideally have a role in all three films.
I think Jericho should have a role but not in all of the films, maybe add him to the team in the second or third one.
In the second film, Brother Blood should be the main baddie but Plasmus, Mammoth, Gizmo, and Jinx could have small roles which would be awesome.
If movies for Flash, Wonder Woman, Aquaman and Superman feature origins for Kid Flash, Wonder Girl, Aqualad and Superboy respectively, itd be cool to have them on the team. But without that, and for them to just show up in Teen Titans would be weird.