In the first season, she wasn't a main character by any means but still got a decent amount of screen time. 8 focus episodes (according to Bulbapedia), which I'd wager isn't bad at all. Overall, she seemed to be coming along promisingly as a character and rival.
In season 2? 30+ episode long gap between appearances. One focus episode. Did reasonably well in round 1 of the league,
No more appearances for the foreseeable future.
What happened? Do the writers have a grudge against her or her voice actor or something? Was this the result of a popularity contest or what?