>>30049744She really isn't a mary sue at all but the problem with her is that at one point in the story it just feels like she just takes the spotlight away from you.
The story starts out as your journey across Alola and it ends up with you working as Lillie's bodyguard as she sorts out her mommy issues.
Lillie and her family are cool characters but the way the story just ended up being more about them rather than you is ridiculous. Black and White were also more about other characters, but the main character actually felt important to the story and not just somebody whose entire journey was hijacked.