Red: At the time of birth, it has just one tail. The tail splits from its tip as it grows older.Yellow: Both its fur and its tails are beautiful. As it grows, the tails split and form more tails.Gold: As it develops, its single white tail gains color and splits into six. It is quite warm and cuddly.
Prof. Lotus' Notes: Vulpix is a portmanteau of vulpine (something that resembles a fox), and six (number of tails it has). Vulpix is derived from Japanese folklore of a Kitsune 狐, which can be translated as fox or conversely, demon fox. The number of tails it has denotes how powerful the spirit is.