From Bulbapedia, the community-driven Pokémon encyclopedia.
Katrina (Japanese: クミコ Kumiko) is a character of the day from the Pokémon anime who appeared in Time Warp Heals All Wounds.
She is the granddaughter of Edna and Jonathan. She told May that her grandfather had left her grandmother to work in the big city and died there, and that her grandmother had lost a very important amulet during that time.
After May and Meowth rewrote history, making sure Jonathan wouldn't leave and stay with Edna, she appeared as her grandparents' helper in care of baby Pokémon. Because of May altering the past, Katrina didn't remember May anymore.