with Wally West dead, we currently have on the roster Nightwing, Starfire [original titan], Aqualad [came over formthe team], and Tigress [Artemis, coming from solo work after Wally's death]
YJ characters still available:
Males- Static Shock, Robin/Red Robin [Tim Drake], Lagoon boy, Beast Boy [arguably a original titan as well], Superboy, Blue Beetle, Impulse/Kid Flash [Bart Allen]
Females- Miss Martian, Wonder Girl, Batgirl, Zatanna, Rocket, Tempest
Nightwing is the one calling this team together, and he would be operating as the effective leader.