The character you're likely thinking of is Misty, one of the main characters in the Pokemon anime series. She appears in many of the Pokemon movies, but there's no definitive number because she's not always a primary focus.
Here are a few examples:
* She is a prominent character in:
* Pokemon: The First Movie (Mewtwo Strikes Back)
* Pokemon 2000
* Pokemon: Jirachi Wish Maker
* She has smaller roles in:
* Pokemon: The Power of One
* Pokemon: Destiny Deoxys
* She does not appear in:
* Most of the later Pokemon movies
If you'd like a more specific answer, you could ask about which Pokemon movies Misty appears in and we can then tell you the total number!