"Advocate" comes from the Latin "ad" and "vocare" (literally "to call to"). I suppose that one could call to someone for someone else, but the denotation of this word requires that we not employ the redundant "for." To advocate a thing is to be "for" it already, making the idea of advocating "for" something not being for it, but being for whatever is for it.

So, it is always "advocate," never "advocate for" in a verbal form. As a nominative, of course the label is required to indicate to whom an advocate is attached.