The Uma Uma no Mi is a Zoan-type Devil Fruit that allows its user to transform into a horse hybrid and a full horse at will. It was eaten by Gan Fall's bird, Pierre.
In the Viz Manga and FUNimation dub, it is called the Horse-Horse Fruit.
Strengths and Weaknesses
This fruit allows the eater to transform into a horse or horse hybrid at will.
This fruit does not seem to have any specific weaknesses, aside from the standard Devil Fruit weaknesses.
Usage
The main usage of the Devil Fruit is merely allowing Gan Fall to claim that he rides a Pegasus, as Pierre's original bird form is big enough already to serve as a mount. However, as a horse or in its hybrid form, Pierre can also bite anyone who disrespects his master.[2]