Pu'ar is a soft-spoken shapechanging blue creature and the constant companion of Yamcha. The name is revealed to be a pun on Pu-erh tea. Pu'ar is neither a cat or a mouse, albeit the series creator Akira Toriyama stated that he had drawn the character to look a little bit like a cat. Traveling alongside Yamcha, the two worked as a team robbing anyone traveling through the desert area in which they lived. Pu'ar has an innate ability of levitation or flight, and is nearly always seen simply 'standing' in thin air at about human head height.
Pu'ar has the unique ability to shapeshift into any form, even inanimate objects, and can hold that form for as long as desired; though strength is not increased by the change, however, as such is unable to turn into something that can be used up like fuel or food. Pu'ar graduated from the same shapeshifting academy as Oolong, although unlike Oolong, Pu'ar had completed all of the academy training and does not have Oolong's difficulties with maintaining a transformed state. Pu'ar shows up quite a bit in the beginning, but becomes less of a presence as the series continues. As the driving theme of the series is mostly about fighting, Pu'ar can do little more than react to the horrors of the latest supervillains in the story.
There is some debate regarding the character's gender. Despite being portrayed by several female voice actors, the character has been referred to with both male and female pronouns during the anime. Though the issue of gender is never directly addressed, Toriyama has referred to Pu'ar as "he" while answering a fan question in the "Ask Me Anything" section in the back of the manga. Some fans believe that since shape-shifters can assume many different forms, gender is a moot point.
(Spurce: Dragon Ball Wiki)