No, "Uncle Martian" isn't a wacky new animated Pixar film. As far as we can tell, it's the name given to a bootleg sportswear brand in China looking to capitalize on the success of Under Armour. Not only do the names sound similar (despite being worlds apart semantically), Uncle Martian's logo is a pretty direct rip of Under Armour's.
It's tough to tell what the brand is all about from these images spotted on Chinese site Shoes.net. If Google Translate is to be believed though, Uncle Martian will be the source of "comfortable, excellence and innovation so that consumers can enjoy at any time in life sports brand mission. [sic]" Sounds cool.
Making things even weirder is the strange presence of what looks like a Nike Air Presto Flyknit knockoff in the image above.
The approach here is similar to that of Qiaodan, a company that's been using a transliteration of Michael Jordan's name to sell bootlegs in China for years now.