I generally use a mix of Pravana and sometimes Rusk haircolor for fun unnatural colors like that. For a pastel shade, I dilute the color with conditioner.
I am a hairstylist and the colors I use are professional. They’re much easier to remove from your hair when you’re ready for a change!
I always pre-lighten the hair (unless it’s already blonde) so the color looks great and lasts longer.
Pastels and peek-a-boos are sometimes easier to get away with at work!
Thanks for asking!