Fairy-type Pokemon are still pretty new, having just been added in Generation VI.
There were several already existing Pokemon and some moves that were changed to Fairy-type when it was implemented. Many of those have become powerhouses of the category.
Some of them are amazingly bland, though. Fairy-types are supposed to be a fresh and exciting opportunity in Pokemon. Like the other types, however, there are some underwhelming Fairies.
Note: This article is subjective. It reflects the opinion of the writer and does not reflect the opinions of others.
5 most underwhelming Fairy Pokemon of all time
#5 - Aromatisse
Aromatisse was one of the Fairy-type Pokemon introduced in Generation VI. Unfortunately, the newer Pokemon can't hold a candle to the original Pokemon that were modified to be a Fairy-type. The likes of Clefable, Togekiss, and Wigglytuff are just too good. That immediately saw Aromatisse take a backseat. It doesn't have a unique moveset or anything to set it apart.
#4 - Slurpuff
The same can be said about Aromatisse's counterpart, other version exclusive, Slurpuff. It was doomed from the start with so many solid Pokemon receiving the Fairy-typing. There is nothing that causes it to stand out. The moves it learns by leveling up are awful. The moves by TM/TR are okay, but there are so many better choices to put those moves to use.
#3 - Klefki
Klefki is one of the dreaded inanimate objects turned Pokemon. It is literally a living set of keys that floats. There is nothing special about it whatsoever. Klefki has no evolutions. Its leveling moveset is atrocious. Its design is rather plan and uninspiring. Klefki is a Pokemon best kept in the PC and for Pokedex completion purposes.
#2 - Carbink
Carbink is another Pokemon without much a purpose. It is the Jewel Pokemon with a body made of crystals. As a Rock/Fairy-type, it doesn't represent either type category very well. While it is a beautiful creature filled with jewels, it doesn't do much else. It can't battle, it isn't on the list of friendly Pokemon, and it can't even be bred due to being genderless.
#1 - Comfey
Comfey is the Pokemon equivalent of a lei. This is another example of random objects of the world being designed into a Pokemon. Comfey is a creature that is beautiful and has plenty of lore purpose. Other than that, it has no true purpose for Pokemon fans and players of the games. It is the smallest Pokemon ever with no further evolutions. Underwhelming is an understatement.