From the way it came off, it seemed like Riki was a last-minute addition to boost ratings. Much like OhBlocker and TackleBoy. Dragonranger, Kibaranger, Kurokishi, and TimeFire weren't part of the main team but they were written with a definite purpose. (Though you could say Dragonranger fulfilled his purpose once his one arc was complete and did little since.) Riki just appears randomly. They never even try to get information about the Pangean civilization from him or how they can defeat Baranoia. Riki never adapts to the modern lifestyle as far as wardrobe goes. (Something I didn't like in Zyu or Ginga either). He's more or less neglected as a character.