Who You Gonna Call?

Olivia, with flashlight and her yo-yo in hand, was heading to the basement to look for monsters. When she came back up, I asked her if she found any and she said -"yes, but I scared them all away". I asked her what they looked like, she said, "Oh, they were pink and some were purple. They had polka dots, and some had stwipes." Can you guess what her favorite colors are?
Now there's one intimidating monster hunter!