I tend to think of a pure boxer as a fighter who goes into virtually every significant fight knowing for a fact that he lacks punching power so that he cannot possibily win the fight if he and his opponent land the same number of punches in every round. So, a pure boxer is a boxer who uses a game plan of trying to avoid punches in order to stack up as high a disparity in punches landed as possible in order to win.
For "pure" boxing favorites with but average speed, but sheer technique... Tippy Larkin Billy Graham Willie Joyce
The absolute perfect answer. Airtight defense, beautiful jab, chin tucked in, right hand almost fixed in place protecting chin, superb slipping of punches and just wonderful footwork. Fammo was the epitome of a "pure" boxer.