Reiko

Reiko is a character of the day who appeared in The Purr-fect Hero (EP053).

Reiko is a sweet lady who is sometimes hard on the children of the school. She had promised the children that she would let them see some Pokémon for Kids Day. However, the three Trainers she wanted to bring were unable to show up. Because of this, Ash and his friends offered to let the children see their Pokémon instead.

(Source: Bulbapedia)