Tamami

Theresa is a character of the day who appeared in Cooking up a Sweet Story. She works at a Sinnoh bakery café and is Abigail's niece.

Dawn and Ash were having a practice battle when Theresa came along and commented on Pikachu, wanting to borrow him for her grandmother. She explained that Abigail's Pikachu, nicknamed Sugar, ran away. After a bit of convincing, Ash finally agreed, as it was only for a few days. Her substitute scheme initially worked and cheered Abigail up, but Abigail soon discovered that Pikachu wasn't her Sugar because of the way he collected the Aspear Berries.

When Team Rocket came and tried to kidnap Pikachu, both Theresa and Abigail chased after Team Rocket's mecha. She was just as surprised as anyone when Sugar came back, now evolved into a Raichu.

(Source: Bulbapedia)