I only thought of Hilda for now, Leaf I never thought of as a character if I'm honest, maybe being one of the people who caught a Starter Pokemon before Ash, I also saw her as Ash's sister and I liked that premise, I know you ship them both but I don't. I wouldn't trade anyone for the established Pokemon groups.
Now going back to Hilda, she is the one facing N and part of the plasma team in the N clashes ideas, she is helping Satoshi establish himself in what he is looking to end (her goal being to end Team Rocket) and Hilda, Team Plasma.