What are boxing signature move?? Two that comes to my mind is young mike right hook to the body right uppercut and ward double left hook (head first body second). It was almost surreal that whenever these guys would land these move, they would either get a kd or have their opponent seriously hurt. I guess you could also add ali pull counter to the list. Clarification: regular single punches are not included, so for example hearns right hand or olivares left hook doesnt qualify. As to be something that is, if not unique, at least pretty unusual
Ismael Laguna's inverted one-twos. Coming in at odd angles, jabbing, crossing then jabbing again. Really threw some top level technicians.
Duran would slip a right hand, and counter with a right uppercut to the body, left hook to the body, left hook up top. Arguello is the other guy who often countered with right uppercuts to the body.
Roy would often nail guys with a lead right, followed by a left uppercut. Sometimes it was a pure uppercut, other times it was that famous hookercut he threw.
More of a tactic than a physical move, but Mayorga letting opponents have free shots. One Roy Jones used to do a fair bit was a walk away appearing like he was trying to reset, than throwing a leaping left hook instead to catch the opponent off guard.
Prime, pre-Rosario Camacho would often throw a one-two, followed by a double, or triple right hook to the body. All five punches thrown in like a second.