Young Justice, in my opinion, is one of the greatest comic book animated shows to ever exist. It would make an absolutely fantastic live-action show that could easily tie in with Flash, Arrow, Supergirl, and Titans.
Robin- Dylan O' Brien:
He would make a fantastic Robin he has boy-hood charm and sarcasm to back it up.
Superboy- Steven Strait:
He has the look down and he's a great actor. I didn't want to pick Robbie Amell because he's fan casted as Superboy by everyone, plus he's already Firestorm.
Miss Martian- Anna Kendrick:
She can play awkward and cute. Those are two great assets for an actress to play Miss Martian.
Wally West- Tom Felton:
Tom is obviously known for Draco Malfoy in the Harry Potter series, so he can bring the sarcasm to it. Plus, he's a naturally funny and kind guy he could nail this role.
Artemis- Emily Osment:
Emily Osment is awesome, she just needs her superhero start already, this would be an awesome role for her.
I saved my favorite character for last!
Aqualad- Tyler James Williams:
Tyler James Williams was awesome in the Walking Dead recently as Noah. He got his start on a Sitcom where he played a young Chris Rock called, 'Everybody Hates Chris.' He could bring the strength and leadership to this role that it would require.