The “Mallow” gag will never not be funny lol
I agree with this list though. I think a lot of people give Serena too much flak and overestimate the Alola girls. Where would you rate Tracey?
Mallow's a weird case since she has barely any battle experience, yet got a fully evolved Tsareena with almost zero training plus a mythical literally jump into her arms. She did master a Z Move legit however so she has that I suppose. Shame she never tried a double battle with Tsareena and Shaymin, she might have been dangerous with healing moves.
Granted in terms of trainers being plot armoured power boosts over training for them, just about EVERY LAST ONE of them is guilty of that to some degree. Even Dawn just got a Togekiss out of nowhere. It's harder to rate Goh too bad in that particular area because of it, when's the last time a trainer caught a Pokemon by BATTLING it after all?
Lana's a weird character to figure out, since it's kind of gag territory how good she is at everything naturally. She never really got a fair opponent, either going against a novice like Mallow or a total powerhouse like Guzma that even Ash struggled against. Serena suffers a similar issue, she only ever finished a battle against someone decisively weaker than her like Team Rocket.
Lillie meanwhile has the brains to battle competently but her Pokemon are barely bulked up. Again, though, she at least has a Z Move.
Tracey was so underplayed he suffers a similar issue of being hard to figure out, though I suppose Scyther gets at least some brownie points for not just beating Team Rocket but ALL OF THEIR POKEMON AT ONCE.