In bea's concept art
She's no zarya but i'd save that for a rock gym leader
I'm late to this but I like this design precisely because it's a mix of styles.
Not sure what the kneepads are for but if we're talking Muay Thai like the Thai shorts would suggest I'd think she'd have shin guards or ankle wraps instead. But no gloves makes me think she's a grappler, and the rash guard covering her torso leans that way. On days where the Brazilian Jiu Jitsu people at our gym roll without Gi they wear rash guards for their legs and upper bodies, usually shorts on top. That shirt reminds me of this Hayabusa branded shirt that I own which kind of looks like a graphic tee but with a small collar and ultra light and breathable.
From a complete outside perspective to the series (haven't played Pokémon in years) I think it's pretty cool, looks like she's ready for any kind of sparring or rolling at the gym.