Underdog - Season 1 - Eps 2: March of the Monsters
An army of giant robots take over the city and capture Polly. Underdog foils the monsters by using his high-pitched voice to destroy the robots' electronic brains. The robots aren't the only thing destroyed, but so is all of the city's glassware.
About Underdog

Title: Underdog
First Air Date: 1964-10-03
Last Air Date: 2000-02-01
Status: Ended
Rating: 6.2/10 (from 22 votes)
Language: EN
Seasons: 4
Total Episodes: 125
Network: NBC
Genres: Animation, Comedy
Production Companies: Total Television Productions, Leonardo Productions
Synopsis
Underdog, also known as The Underdog Show, is an American Saturday morning animated television series that ran from October 3, 1964, to March 4, 1967, starting on the NBC network until 1966, with the rest of the run on CBS, under the primary sponsorship of General Mills, for a run of 62 episodes. It is one of the early Saturday morning cartoons. The show continued in syndication until 1973. Underdog, Shoeshine Boy's heroic alter ego, appears whenever love interest Sweet Polly Purebred is being victimized by such villains as Simon Bar Sinister or Riff Raff. Underdog nearly always speaks in rhyming couplets, as in "There's no need to fear, Underdog is here!"
Cast

Wally Cox

Sandy Becker

Kenny Delmar

George S. Irving

Mort Marshall

Norma MacMillan

Delo States

Ben Stone

Allen Swift