© PA Photos
Blackpool began to find their stride through Stephen Crainey, who had two shots saved in the first 15 minutes until Thomas Ince found the breakthrough.
Ince collected the ball from Elliot Grandin, who provided a smooth pass into the six-yard box, which Ince managed to fire into the middle of the goal.
The home side tried to force through an equaliser before the break but Chris O'Grady and Bothroyd failed to make an impact for the home side.
Blackpool tried to double their lead after seeing through some early pressure from Wednesday in the early stages of the second half courtesy of a shot by Sylvestre.
Sylvestre's shot was unable to get through Watford's defence but minutes later an in-swinging corner by Grandin fell to the near post but Ross Barkley managed to clear to safety.
Minutes later Sylvestre managed to get a second chance on goal, which he was able to convert after his initial chance was rebounded off goalkeeper Chris Kirkland.
Sylvestre collected the ball and launched his shot into the top-right corner of the net to kill off the game and secure three away points.