Mika

Mika is a character of the day and a little girl who lives in Megi City on Yellow Rock Isle with her sister, Andrea, and their father. The entire family appeared in A Corsola Caper! (EP215).

The family's business collects Corsola horns to make jewelry, the main source of income for Yellow Rock Isle. As a result, the family lives on top of a Corsola colony. This gives them easy access to the Corsola when they shed their horns.

One day, an overexcited Corsola found its way to the family. Its eagerness to play scared off all the other Corsola. Because there were no Corsola in the colony, their house floated away. Unfortunately, it carried little Mika with it. Thankfully, Ash and his friends saw what was going on and came to Mika's rescue. With the help of Bulbasaur and Bayleef, Mika was saved from drowning in a whirlpool.

She reappeared in a flashback in Espeon, Not Included (EP228).

(Source: Bulbapedia)