What is Pleader?

Legal Definition
A person whose business it is to draw pleadings. Formerly, when pleading at common law was a highly technical and difficult art, there was a class of men known as "special pleaders not at the bar," who held a position intermediate between counsel and attorneys. The class is now almost extinct, and the term "pleaders" is generally applied, in England, to junior members of the common-law bar. Sweet. See Special pleader.
-- Black's Law Dictionary
Legal Definition
One who prepares a pleading or pleadings.
-- Ballentine's Law Dictionary