Cassandra and her grandmother owned a medicine shop in Mossgreen Village. When Ash and his friends met up with her, she was trying to get her Paras to evolve, because she needed Parasect's mushroom to make a specific type of medicine. In an attempt to help her Paras evolve, Ash battled it using his Pikachu, Squirtle, and Charmeleon. However, all he did was end up scaring it off.
Meowth was rather smitten with Cassandra, although it talked Jessie and James into cooperating by telling them of the fortune they could make off the miracle potion Cassandra wished to make. He believed that this would also give him a good home with Cassandra. Thanks in part to Team Rocket, Paras ended up evolving and Cassandra was able to make the medicine she needed.
As for Meowth, his luck ran out when Cassandra's Grandmother found a Persian sleeping in the backyard and kept it instead.