"Fortune Fairy", known as "Fortune Telling Witch" (占い魔女Uranai Majo) in the Japanese version, is an anime-only archetype consisting ofsix6 monsters, each named and colored according to their own Attribute. The card text on each "Fortune Fairy" tells the fortune of the person who draws it, along with a listing of a lucky number, color and item.
In the first episode that they were used in a Duel, it appears that their play style focuses on summoning as many as possible and as fast as possible, using cards such as "Luck Loan" and "Unacceptable Result", then using "Miracle Stone" to increase their ATK.
All of these cards have a fortune written on them, with lucky number, color etc. The lucky color and number correspond to that monsters' Attribute and Level. The fortune may be based on the luck of you having it in your hand, e.g. it would be unlucky to have a level 6 Normal Monster with 0 ATK and DEF.