There have been hundreds of art movements. Cubism is just one, and while it is popular with some, it is not the most famous, at all.
Cubism was.
He was famous for cubism art, but I'm not completely sure what his most famous artworks are.
He is most famous for cubism.
He prduced a number of styles. Most famous is Cubism.
The founders of Cubism are generally considered to be Pablo Picasso and George Braques.
Picasso covered many different styles, but he's most famous for cubism.
Cubism
As with any art movement, the choice of most famous or popular is very subjective. One way to gauge how famous or popular a particular style is would be to review what art collectors are buying currently. Of the three mentioned Cubism may be the most infamous due to the public's outrage when the paintings were shown.
He has been famous for his cubism which he made up
Pablo Picasso
Pablo Picasso
I do not think this statement is true. Cubism is well known, but so are other movements. I believe more people know about (and like) Impressionism. Probably also Italian Renaissance.