Pegasi

Pegasus ponies, or Pegasi, are ponies characterized by their wings and their ability to fly and manipulate clouds.

Development and nomenclature
Pegasus ponies were introduced shortly after Earth ponies in the original My Little Pony toy line. On the show, they are called either Pegasus ponies or Pegasi, and mostly "Pegasus" for a single pony, though "Pegasus pony" is also used, as specified in the article ponies. Lauren Faust, the show's developer, stated that the Pegasus ponies have a passive kind of magic that allows them to walk on clouds and manipulate the weather.

Depiction in the series
Pegasus ponies possess wings. They are capable of great speed in the air, though not always as fast as Earth ponies on foot, as seen in Fall Weather Friends. While competing for the title of Iron Pony, Rainbow Dash is equally matched with Applejack, an Earth pony. Several other Pegasus ponies who participated in the Running of the Leaves are seen panting in exhaustion at the end of the race. Pegasus ponies manipulate the weather in several episodes, moving clouds to either cause a storm or clear the skies. In Sonic Rainboom, they also create snowflakes and rainbows in special factories.

Pegasus ponies have a unique ability among ponies to naturally walk on clouds, which is elaborated upon when Dash's friends wish to cheer her in the Best Young Flyer competition. This ability is not limited to Pegasus ponies; Gilda, a griffon, is also seen walking on clouds, and in May the Best Pet Win, several other creatures capable of flight perch on clouds.

The Pegasi's role in the founding of Equestria is depicted in Hearth's Warming Eve. The pageant in the episode features a Pegasus tribe, who are led by Commander Hurricane, played by Rainbow Dash. Commander Hurricane wears battle armor, as a sign of high-rank, and refers to the Pegasi as "a mighty tribe of warriors".

Residence
Pegasus ponies are mostly seen in Ponyville, where all three types of ponies reside, and Cloudsdale, exclusively populated by Pegasus ponies since they are the only type of pony that have the natural ability to walk on clouds. Rainbow Dash, a well known pegasus, has her own cloud stylalized house. No Pegasus ponies have yet been seen in Manehattan which was only shown in The Cutie Mark Chronicles. Canterlot is almost devoid of Pegasus ponies, with the exception of Celestia’s royal guards, who can be seen carrying her in a flying chariot in Swarm of the Century. Another pair of royal-guard Pegasus ponies carry Twilight Sparkle in a similar chariot in the first episode.