he doesn't join in an actual episode. only in the comics.
It is most likely that he left batman because of the same reason he left him in the episode of batman where Dick grayson (robin) tells Tim Drake (third robin) that he left because his girlfriend became batgirl without him knowing and her in danger. If another season of Teen Titans is ever written Dick will probably be portrayed as Nightwing as he was in that episode of Batman and the episode of Teen Titans where starfire is sent into the future
Episode 13
He was drafted by the Titans in 2006.
You can join, but you need your parents signature. ( also depends where you live)
season 1, episode: The Power of Madonna.
233
In order to be in WWE they have to offer you a contract, you don't just join it is not that easy./
Sasuke joins Orochimaru in the end of episode 109 but everyone(except Sakura) finds out in episode 110
after he killed his clan. It wasn't on any episode, it happened before the main storyline.
If you mean what episode she became part of the team for temporarily it was season 7 episode 6 "Office Politics."
Episode 33 in the anime
Tennis,chess,language,basketball or cooking club!