The Teen Titans have gone through many incarnations through the years, but basically they're DC's premiere teenage superhero team.
Stephanie first became involved with the teams in it's 1990's incarnation, when she and Tim went to Titans tryouts in Teen Titans (second series)(17). However, they both eventually decided not to join, being too busy in Gotham.
Stephanie made a guest appearance during the time she was Robin in third series of Teen Titans #13. This incarnation of the team had Tim as a member, as well as Superboy (Kon-el), Wonder Girl (Cassandra Sandmark), Kid Flash (Bart Allen), Raven, Starfire, Beast Boy and Cyborg. Superboy noticed Tim has been missing a while, and went to Gotham to find him. He was nonplussed to find Stephanie in the Robin costume, and demanded to know who she was and why she was wearing the costume.
Stephanie was polite, considering how Kon treated her, but Batman decided to intervene, telling Superboy to find Tim himself. Kon yelled after the retreating Steph and Bats, "You, Robin, are not welcome at Titans Tower! We already have a Robin! Don't we?"
Kon tracked Tim down, and Tim informed him he had quit superheroing. It was then Kon finally recognized Stephanie's voice as "your ex-girlfriend! Spoiler, or whatever it was she called herself!" recalling her times with Young Justice. Tim replied that Stephanie was "a strong young woman" and worthy of the mantle, and Kon left in a huff.
Tim mentioned Steph in Teen Titans #50 in the list of people he's lost and mentioned her return to Wonder Girl in #62.
Stephanie appeared in Teen Titans #66, though it was revealed she only came along to give Tim moral support as he quit the team. However, she is now a direct ally to the Titans, and presumably their security system accepts her. She made friends with both Cassandra Sandsmark and Traci Thirteen, sparring with the latter in the Titans exercise room. Steph admired Traci's combat skills, considering the girl didn't have to rely on magic. Traci thanked her but told her to stop holding back, and Stephanie complied by easily taking Traci down with a kick to the face. Traci responsed favorably though, saying, "Nice one!" and Steph helped her up.
Her interaction with Amy Allen, the former Titan traitor and semi-member Bombshell, was less favorable. Bombshell came in challenging the two girls, and Traci refused, attempting to defend herself and Steph saying a "trashy traitor" like Amy wouldn't play fair. Bombshell dismissed Traci and continued insulting Spoiler, asking if she was chicken, or afraid that she's die for real this time. Stephanie visibly tensed and glared, but the argument was interrupted by hyperactive teen hero Misfit teleporting in.
Wonder Girl later interacted with Spoiler some more, saying it was great she wasn't dead, to which Stephanie replied, "Yeah, I kinda like it," and then talking to Steph outside Tim's room before Steph skeddadled to a guest room in the Tower.
Stephanie left the Tower with Tim in the Bat-Plane after he quit.
Stephanie and the Teen Titans: