in the episode "Treasure Mountain" our heroes end up fighting Pisarro in an ancient Inca temple. gold will make people do strange things. somehow, Pisarro manages to have enough money to create several robot worms to help him along in his quest to steal the Incan gold.
this series has some great shots of Gigantor powering up. it gets made fun of for it's rather limited animation, but they really got the most out of it.
here's the robot ape "Tiny" battling Gigantor. there's a lot of humor in this fight, and it's intentional from the Japanese side. when the series was redubbed they added a lot of verbal humor that wasn't always present.