If you beat Richie, you'll go on to face a few more challengers, and then the Elite Four, and maybe a champion. Ash was top 16, which means had he won he'd be top 8, which means there should only be three more challengers after Richie and before the Elite 4.
Good. By Elite Four, do you mean Prima (Anime name; Original name: Lorelei),
Bruno, Agatha and Lance?
And also, when we face Team Rocket, is it going to be a double battle?