Miss Priscilla is a teacher at Earl's Pokémon Academy who works with young children just starting out in Pokémon training. She showed up in the episode "A Bout With Sprout."
Ash and friends first encountered her when she stepped in to stop a couple of her students from smothering Pikachu with too much attention. Brock was instantly smitten and volunteered to show the kids his group's Pokémon—an offer Miss Priscilla happily accepted, letting them all into the school. Unlike Ash and Misty, she didn't mind Earl Dervish's constant spinning around; if anything, she appreciated his energy.
She's genuinely invested in her teaching approach, favoring hands-on learning. She happily had Ash's group let her students interact with their Pokémon directly and organized field trips to give lessons real-world context. She's clearly proud of her community too—she answered questions about the Sprout Tower and eventually took both her class and Ash's group on a tour there. Her students clearly respect her; they listen well and followed her instructions without fuss, like when she had to evacuate everyone as smoke filled the tower. She was visibly upset about Team Rocket's destruction of the Sprout Tower, knowing how much it meant to her kids.
Content compiled by AnimeList.moe from publicly available sources.