According to IGN, here are the ways to unlock all (currently posted) hair colors in PLZA (currently, they all involve The Many Colors of Flabébé quest, see linked article for instructions for the quest):
Aqua/Orange/Passion Pink/Purple:
Catch All Flabébé for The Many Colors of Flabébéside side quest (final reward).
Blue/Lemon/Orange/Red/White:
Catch the corresponding Flabébé in The Many Flowers of Flabébé side quest.
Important Note:
The source page might not be complete! I will update this answer if any more hair colors are discovered and posted on that IGN article!
Ok everyone, I've been dared to achieve more points than SiIver. Instructions: hack into the DB, change the fact that you don't get points for upvotes after 20 votes on a post, and spam upvote this answer. I bet SiIver is so terrified that they're going to remove this paragraph.
