Right now, the only two characters that are confirmed to be involved are Batgirl and Nightwing, but others are expected to be featured too.
The last few years have treated the Teen Titans in a really good way. The teenage superhero team was actually pretty overlooked on the big screen, but 2018 gave us both their first cinematic outing in the surprisingly enjoyable 'Teen Titans Go! To the Movies!'. Not only did they get a movie, but the also got their first live-action TV series titled DC Universe’s 'Titans'. As reported by We Got This Covered, the teen team might be heading towards the big screen soon as a live-action film could be on the way.
As revealed by the source, Warner Bros. is working on a movie for the Teen Titans and it will be titled as 'Young Justice League', and it seems like the project will lean closer to the Young Justice team from the comics and the highly-appreciated animated series. Right now, the only two characters that are confirmed to be involved are Batgirl and Nightwing, but others are expected to be featured too.
Regarding the villain of the story, the current choice is HIVE and he is regarded as the main threat. This organization of a group of villains has been a threat to The Titans for a while now in the comics. Along with this, they have also appeared in Arrow season 4, hence it is safe to say that they are a decent and good pick as the main antagonist of the story. But, the source also mentioned that their involvement is not 100% certain as of now.
For now, what we know is that it has been confirmed that the Teen Titans/Young Justice movie will take place in the new DCEU continuity and in our previous articles, we have also mentioned that the DCEU Universe will be split in two in the future. The old franchises will be continued along with the original universe and any new projects will be a part of the new universe. So, the Titans will exist along with 'The Batman' and 'Supergirl'. Even though we have to wait for a while to see the Teen Titans movie, the TV series 'Titans' season 2 is currently in production and will arrive later this year at DC Universe.