Fairy-type Pokémon are generally considered "cute" and tend to be at least partially pink in color and feminine in appearance overall. However, Fairy types can be incredibly powerful. Fairy types also have some magical appeal to them. As opposed to Psychic-type Pokémon, Fairy-type Pokémon have powers related to magic and the supernatural as opposed to mental power.
The only known famous Fairy-type Pokémon Trainer is Valerie, the sixth Gym Leader of the Kalos region.
They're weak against the Steel type because according to European legends and traditions, fairies could be killed with iron due to it being man-made and manufactured, which is opposite to the natural affinity of fairies. Also, in some stories, fairies could not touch steel because it burned them when touched.
They're weak against the Poison type because fairies represent purity and poison can represent pollution. Also, in some stories, villains gave fairies poison to weaken them.
They're strong against the Dragon type because in certain mythologies, fairies' magic could dominate oriental dragons, even though in European legends dragons were immune to magic.
They're strong against the Dark type because fairies represent light and darkness disappears with light. Also, fairies represent goodness and this always wins against evil, which the Dark type represents.
They're strong against the Fighting type because physical strength is virtually useless against magic.
They resist the Bug type because in many forms of popular culture, fairies live among insects and bugs.
The Fire type resists them because traditionally, fairies live in forests, which fire can easily destroy.