Despite Shredder's failings, he is still shown to have considerable skills. In martial arts, he is often shown to surpass the Turtles and to be equaled only by Splinter. Nevertheless, he usually runs away from a fight when outnumbered, incapacitating the Turtles to defeat them in combat; as the series progressed, however, the Turtles were able to battle him on more equal grounds and even defeat him in combat on several occasions. He trained the Punk Frogs in a very short period of time to be a match for the Turtles, but the Punk Frogs soon switch sides. His technical skills are also quite impressive: he designed and built a robotic body for Krang, prepared the mutagen mixture, knew how Krang's teleportation engine worked, and built numerous other advanced devices. Ironically in one episode "Shredderville" the Turtles dream they find themselves in a mirror universe where they themselves never existed and Shredder rules New York City, yet finds the task of ruling so burdensome that he has a nervous breakdown.