I'm doubting she'll even get one. What use would a rival do her? Her main focus as of now is Axew getting stronger and evolving, and most likely she'll start paying attention to Excadrill not listening to her and train with it or something and have it listen.
Rivals aren't really needed for that. So unless she gets something else to do I don't see it likely that she'll get a rival at all.
Not every character needs a rival after all.
In my opinion anyways.
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