Lana isn't bad conceptually, but she is pretty one note. She has quirks but they don't really play enough into long term development or synergy with the rest of the main cast. She is more a gag character with a few likeable traits, a lot of her shtick is how cheaply OP and perfect she is. It's funny enough as an episodic gag but doesn't really work as a protagonist we're supposed to be invested in, especially since she's barely done more than the other two main girls this series. Her Pokemon aren't handled great either, Popplio might be the blandest of the six signatures, so much she was among the few to actually get demoted after evolving this series, while Sandy, despite having a personality, is limited to inactive comic relief.
Lana likely would have worked better as a recurring character or a classmate from another section of the school. Ilima and Acerola similarly lack much in terms of flaws and dynamics, though because they are only seen in doses as supporting characters it doesn't feel a let down as their personalities still hold enough for what their roles demand to make them charming. Not to mention keeping them out of focus makes it more believable they'd be good at something like battling despite no limelight concerning it, while the show seems to be awkwardly trying to shoehorn in Lana as a powerhouse despite not giving her a single competitive battle the whole series, likely with the excuse 'oh but she's good at everything anyway'. This is where she doesn't work as a main character we are watching all the time because her gag character laws undermine the actual development of others.
