From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
King Nikochan (ニコチャン 大王, Nikochan Daiō; FUNimation "King Nikochan"; Literally meaning "Nikochan Great King") is the king of the Nikos, an evil, but inferior, race of aliens.
Nikochan and his servant came to Planet Earth after years of trying to find a planet weak enough to conquer. He comes in when he tries to conquer the Earth and finds Arale Norimaki and Gajira Norimaki. He blew up Planet Mars trying to get their attention. Gatchan then ate their ship and left them floating in space all the way back to Planet Earth. Nikochan asked Senbei Norimaki to build him a spaceship, but he instead built him a car. Later on in the series, they got a spaceship only to find that someone had taken over their homeworld. Arale destroyed the ones who had taken over and peace was returned to Planet Nikochan. They later returned for the grand finale of the series.
Nikochan can be seen in the crowd at the 21st Tenkaichi Tournament just before the fight between Kuririn and Bacterian. Later, he was seen back in Penguin Village picking up trash which he mistook for treasure. Afterwards, his servant told him that the police were coming and Nikochan and his henchman got into their UFO that they finally had fixed. They then planned to kill the police and rule Penguin Village, but the police destroyed their UFO for good, stranding them forever.