Pegasi

Pegasus ponies are a type of pony living in equestria, characterised by their wings and ability to fly.

Physical traits
Pegasus ponies all possess wings, these enable them to fly at impressive speed and heights. To allow them to do this pegasus tend to be smaller and lighter than earth ponies, and lack their strength and endurance. They possess great speed both in the air and on foot however, Rainbow Dash was equally matched with Applejack throughout their race in Fall Weather Friends and many other pegasi participated (though the ones shown to be exhausted by the effort were all pegasi).

Magical abilities
The dividing line between physical ability and magic is uncertain in pegasi, however they do have some traits that seem magical in nature. All pegasi seem to have some level of Control of the Weather, manipulating clouds to cause rain or snow and clearing the skies when they are no longer needed. Many also show the ability to Create Coloured Trails in the Sky, which has little practical use but provides an impressive show, as such it is the signature trait of the Wonderbolts. In a similar manner they can create impressive Light Shows and colourful shockwaves. Finally many pegasi live in the sky in cloud cities, they achieve this by their ability to Walk on Clouds.

Place in Pony Society
As mentioned the primary role of pegasi is in weather manipulation. As well as cloud clearing they are also shown to create snowflakes and rainbows in special factories.

Due to their affinity with clouds many pegasi live in sky cities mostly inaccessable by other types of pony, and seem to be rarer on the ground. For instance pegasi were not seen in Canterlot or Manehatten despite the presence of members of both other breeds, and Fluttershy had never even seen the ground before in The Cutie Mark Chronicles despite being quite a mature filly.

Most of the pegasi seen on the show have been very sporty and competitive, and Celestia’s royal guard have all been pegasi. While this may be due to seeing a limited selection, it indicates a definite streak of fierce strength that is present among many of them.