Logan Lerman as Robin
An important aspect of the Robin I grew up with in the Teen Titans animated series was that the show never blatantly came out and said which Robin he was. Dick Grayson, Tim Drake, Jason Todd and a few other hints were dropped but you cared about the character in general because he was compelling. A tough trick for any show to pull off it would force the show to do some serious character development for the leader of the Titans. .
Reasons for Casting: Lerman not only is the actor that looks the part for Robin but he's really suprised me with his growth as an actor since the God-awful Percy Jackson films. He's not taking any small steps either as he'll be starring alongside Brad Pitt in the upcoming war epic entitled Fury.
Tatiana Maslany as Raven
Raven, in my mind, would be the kickstarter of the first season along with Starfire. The pilot would consist of Raven's soul-self being reanimated into a new body and her begining life once again.
Reason for Casting: Orphan Black mostly. Tatiana plays multiple versions of herself and has the ability to make them all distinct which is one of the abilities needed if one were to play Raven, a hero who has multiple incarnations of herself.
Analeigh Tipton as Starfire
The love interest of Robin, Starfire's origin would indeed need to be explained if she were to pop up in the pilot but I feel the best way to do it would be to introduce her character once the show is up and running with some momentum, having her crash to Earth and have the whole "kiss to learn English" thing happen and go from there.
Reason for Casting: Analeigh has the looks for Starfire and definitely is able to bring some life to the character which I feel has been missing for some time. Time will tell if she can be badass but as far as personality she can without a doubt be interesting on camera. The TNT budget goes a little deeper than CW too so let's see some powers.
Hailee Steinfeld as Wonder Girl
Although the picture is of the Donna Troy Wonder Girl I wouldn't neccesarily have a distinction considering the different incarnations share the same powers. A character I've desperately wanted brought to live-action I would replace the popular Young Justice character of Superboy and instead use a more unknown character like Wonder Girl.
Reason for Casting: Steinfeld is universally loved right now with her starring roles and I doubt she would even do television at this point but if she were to I think the Teen Titan Wonder Girl would be the perfect fit. Not a stranger to action, Steinfeld would do well as the relative of DC's own Wonder Woman whether they use Donna Troy or Cassie Sandsmark.
Lyndsy Fonseca as Miss Martian
Going to be honest here, I've been binge-watching Young Justice. I still have zero idea why she's such a fan-favorite but with my knowledge of her I happen to think Fonseca could make a convincing yet badass version of her. I have yet to finish YJ so don't jump on me in the comments section.
Cameron Boyce as Beast Boy
The jokester and comedic relief of the Titans, Beast Boy himself has some pretty heavy drama he deals with as a hero and member of the Teen Titans.
Reason for Casting: Cameron is the perfect choice for Beast Boy for television. He's not a bad actor and he has some pretty great comedic timing as shown in his stints on Disney Channel. With some practice and some effort I think he could become the total package for the shapeshifting hero.
Colton Haynes as Arsenal
Though there's like a 99.9% chance of it not happening I think Titans and the Arrowverse should be connected because not onversaturating the market it best in my eyes. No one is saying Colton has to lead the show, he could die in three episodes for all I care but establish the fact that Arrow and Flash are in the same universe first.
Reason For Casting: He's already the character on Arrow. That's it. People say he's a bad actor but I can't speak on that because Season 3 of Arrow will be my introduction to how well he can act. So don't jump on me in the comments section.
Vanessa Hudgens as Cheshire
The sometimes love intrest of Arsenal, I feel the character could really add the some depth and emotion into the character of Roy Harper and at the same time be a badass weapons master.
Reason for Casting: Hudgens is a decent actress and to be quite honest she looks the part better than anyone I can think of who would appear on TV. She could escape the Disney stigma and possibly escape her pre-Fappening controversey.