As we all know the Teen Titans/Titans are one of the most popular Superhero Teams in the world.
One Movie for them is literally not enough, because of their rich History. They definitely need more love because their potential is really great and If done right, with the right casting and director, it can be easily one of the best Superhero Trilogy's of all time.
1. The first movie should establish the reason to form the team in the first place but it also needs a Deathstroke Cameo that's just my take on that.
It should definitely be a longer movie to establish the Original Titans like The first Robin, The first Aqualad, the first WonderGirl and the first Kid Flash (with the occasional addition of Lilith, Speedy, Hawk and the first Dove, Bumblebee and Tula.)
The Movie is basically just a character driven movie to establish the Key characters Kid Flash, Wonder Girl, (Aqualad) and Robin. The villain should definitely be Mr. Twister to establish the purpose for the creation of the Team, just like in the Comics. The movie should have like 2 Villains. The first one should be Mr. Twister like I said but just for establishing the team. The second and main villain are the fearsome five. Formed by Doctor Light with the addition of Mammoth, Shimmer, Gizmo and Psimon.
The second movie will have a major time jump. Deathstroke is getting hired by H.I.V.E to kill the remaining Titans but because of his rule to never kill innocent *children* he declines, which made the Organization really mad.
Aqualad is going back to the Ocean with Tula because they have a mission to save Mera alongside (Jason Mamoa). Speedy, Bumblebee, Hawk and Dove created their own team because the group had some issue over the years, so they finally split up. Bumblebee is the Leader of the New Titans East.
Dick and Donna were still doing the Hero stuff in the West, especially since Dick quit college to be a full time hero, which didn't please (Robert Pattinson) at all.
Kid Flash did exactly the opposite. He gave up his hero life for education. So after all that little backstory Dick had some weird dreams, caused by Raven. She says that this City needs the Titans. She convinced him (because of the dreams), so he went and tried to convince Kid Flash as well, but he was hesitant. Donna and Beast Boy were fighting criminals that night, when all of a sudden Dick showed up. He told Donna that they are forming a new Team again and she agreed. Beast Boy never met Robin in person so he obviously was kinda fan-boying a little bit.
We see Cyborg devastated and lost. He was missing for months, he called his coach and they met on the training ground because he got kicked out of the Highschool football team because nobody knew where he was. He explained everything but couldn't convince the coach because of the Meta Human rules. While talking to his coach he got mad thinking about the fact that he can't have a normal life ever again, because of what he has become. He blames himself for his mistake but his father more for making him a freak. Raven showed up and tried to give him a new perspective with his new gift/curse he has now. She told him that there is a place where nobody would judge him of how he looks or what he's capable off... but he was also hesitant to follow her.
PROLOGUE:We see Starfire getting attacked by the Minerva Aliens. While fighting with them, she gets unconscious and falls on Earth. Grant Wilson finds her and takes her to his and his girlfriends home. Grant and his GF start arguing (again because of his behavior towards her and everything) and he tells her that he took a Job that pays well but didn't go into detail (just a little bit of foreshadowing). The aliens found her and kidnapped her again (Grant could have stopped it but he doesn't want to give away that he has special abilities)... PROLOGUE end.
A giant explosion accured, so Cyborg rushes to that place after hearing it. He saw someone getting dragged to that giant spaceship when suddenly Robin, Donna, Beast Boy and the late coming Kid Flash showed up. They teamed up, managed to infiltrate the ship to free Starfire and are getting away from the Space ship, while destroying it in the process. After some talking she makes that iconic kiss with Robin for trying to understanding the Language at the end of the first act.
Some weeks/months passed and after some training sessions with the new Team they finally had their first major mission together. The fearsome five are back again, led by Jinx (it's just a minor crime caused by them). They were stopped, which didn't please the H.I.V.E.
They called up Grant to the H.I.V.E Secret base to fulfill his contract. They gave him something to increase his abilities to finally destroy the Titans one by one. After that immense power up he went away and confronted Cyborg first, but he failed got knocked out and Cyborg barely escaped.
Deathstroke found him and took him to his secret base and gave him an advice not to fight the Titans. He didn't listen because he's reckless and a hot head, so he went to fight them anyways without knowing that the Titans were prepared for his arrival. Deathstroke attached a tracking device and came to stop him from doing it. They (Robin, Donna, Kid flash) didn't expect to finally cross paths with Deathstroke, so he fights them and is beating them but before he could finish the job Ravager is suddenly in pain and is dying, because of the side effects of that enhancement. Deathstroke warned him but still blamed the Titans for killing a innocent teenager, which they didn't do.
EPILOGUE: Grant's Girlfriend despite having issues wit him shows up to his funeral. His father was there as well, we don't see him but we hear him talk with Wintergreen.
The after-credits are Terra showing up in Town while fighting Deathstroke and his henchmen.
The 3rd movie is basically the Judas Contract. It should be a long movie especially to let things breathe and explain.