He made his 1st apperance in The R and R theory. He hijacked an Ace Chamicals truck carrieing an experimental isotope. He also robbed an elcrictal generator, a radioactive generator and some connections. He left a trail of riddles in his wake which aloud the Dynamic Duo to track him to his lair in the abandoned studioes which hosted the R and R thory quiz. The 2 found out that the Riddler was Edward Nygma the former host of the quiz who was cut when the quiz was moved to the studioes on Mount Gotham and Jack Ryder took over. He has constructed a laser using the components and plans to destroy the studioes. During a battle between them and his goons the laser was knocked over and began firing all over the base. Bruce used an experimental Wayne Tech teleporter to teleport the laser away but did not know Riddler was strapped to it due to falling onto it. It landed in the water and exploded.
He made his second apperance in Riddlers Revenge. He managed to unstrap himself and swim a few metres away but did not make it far enough away to avoid the entire explosion. It caught his 2 legs sending him flying into the air. He landed on Dr Emmees car. She was a big fan of Edwards work and supplied him with robot legs. He decided to take revenge on Batman and Robin by creating a bomb big enough to destroy Gotham.He stole the neccisarry coponents but once again his riddles led the 2 to him in Wayne labs where Emmees worked. During a battle A stray Robinarang hit his right leg fuel line causing him to walk out of control and activate his bomb. He had never planned to actually usee the bomb just lead Batman to him. He walked out of control as Batman tried to undo the countdown. In the end he used an old Batwing engine to launch it up. Unfortunatly for Riddler his magnetic feet started walking up the giant bomb as it launched. As it went into space the zero gravity made him drift of. As it exploded it launched him towards Earth.
Although he never resurfaced in the cartoon he made his last apperance in Batsy#3. He joined the Leigon of Doom. He and Ratcatcher were sent to distract Nightwing leading him to Metropolis while the others found and destroyed the Bat-Cave. Nightwing got wise to their plans thanks to Azrael and went back to defend the Bat-Cave although he was to late. Azrael stuch his sword into the car bonnet the 2 crooks were in forcing them to flee. Later the 8 members met in their HQ and planned to look at the bat-datachip. When they looked at a screen it was a countdown. 6 seconds later the place blew up claiming all of their lifes.