The series is notorious for its large cast, much of which was introduced in the early games for the Sega Mega Drive and its add-ons: Miles "Tails" Prower, a mechanical genius from West Side Island and Sonic's best friend, first appeared in Sonic the Hedgehog 2 (1992). Sonic the Hedgehog CD (1993) introduced Amy Rose, a pink hedgehog who is deeply in love with Sonic and is known for wielding her Piko Piko Hammer, and Metal Sonic, a robotic copy of the blue hedgehog created by Eggman to be his equal mechanical match. Sonic the Hedgehog 3 (1993) marked the introduction of Knuckles the Echidna, a gullible and short-tempered echidna who serves as the guardian of the Master Emerald on Angel Island, a large gemstone later introduced in Sonic & Knuckles that controls the powers of the Chaos Emeralds. Knuckles' Chaotix (1995) introduced Team Chaotix, a team of detectives consisting of the leader named Vector the Crocodile, Espio the Chameleon and Charmy Bee.