Master of Chaos!
It was during the episode you mentioned, Team Rocket fired a missile in cyber space when Pikachu shot a thunder bolt to blow the missiles up. Then came the flashing lights, many kids that day... had to go to a hospital and since Pikachu was the mascot, he got off Scott Free while Porygon was never seen again! His evolution's never debut in the anime outside of movie cameos.Wasn't that the story of the banned Porygon episode? You know, the one that gave 700 kids in Japan seizures?