A Phanpy's enormous ears are natural fans which are used to not only cool wild Phanpy, but their entire herds, Donphan and Phanpy alike. Indeed, Donphan, with their thick armor and heavy, narrow ears, must reproduce or form groups with other Donphan's Phanpy in order to regulate their own body temperature. Humans have also caught on to the value of Phanpy, and in warm climates they are often preferred for cooling to even ice and water-type pokemon.
Despite these ears producing a fairly strong breeze, Phanpy do not flap them at a high enough speed to use flying attacks such as Gust and Hurricane. It was once thought by science that this was because their ears did not allow for such movement; certainly it would use such an attack to defeat the often dangerous grass-type pokemon they eat if they could! Recent anatomical research on Phanpy, however, suggests that Phanpy indeed have this ability, but refuse to use it, likely because they fear blowing their prey too far away.
Tradition ascribes another reason for Phanpy's reluctance to use Gust. Phanpy are ground-type pokemon, but know few ground-type attacks. Because of this, they find their connection to the ground tenuous, and fear that if they get picked up by too strong a wind, their ears will carry them like a Hoppip across the skies. Today, this theory is usually thought of as an old superstition, but there is a tempting logic to it: if their artificial orange pads are removed, Phanpy ears look remarkably like Lugia or Swanna wings.