Much of the supporting cast was introduced in the succeeding games for the Genesis and its add-ons. "Sonic 2" introduced Sonic's sidekick Miles "Tails" Prower, a fox who can fly using his two tails. "Sonic CD" introduced Amy Rose, a pink hedgehog and Sonic's self-proclaimed girlfriend, and Metal Sonic, a robotic doppelgänger of Sonic created by Eggman. "Sonic 3" introduced Sonic's rival Knuckles, a red echidna and the guardian of the Master Emerald. The Master Emerald, introduced in "Sonic & Knuckles", controls the power of the Chaos Emeralds. "Knuckles' Chaotix" introduced the Chaotix, a group comprising Espio the Chameleon, Vector the Crocodile, and Charmy Bee. A number of characters introduced during this period, such as Mighty the Armadillo and Ray the Flying Squirrel from "SegaSonic the Hedgehog" and Fang the Sniper from "Sonic Triple Trouble" (1994), faded into obscurity, although they sometimes reappear.