The mystery character in Sonic Rivals is Metal Sonic. To win him, you have to beat the game once with every character. Doesn't matter which order. You can also win Super Sonic. but that is Xtremely hard. U have to get a S grade in every level, and every zone.
Triangle at Character select
When selecting character press Triangle
There is no Sonic Rivals Three.
Sonic Adventure 2, Sonic Battle, Sonic Heroes, Sonic The Hedgehog (Sonic '06), Sonic Rivals, Sonic Rivals 2, Sonic Chronicles: The Dark Brotherhood, lastly Sonic and the Black Knight (as Lancelot).
Sonic the Hedgehog 06 features his only appearance as a character in a Sonic game. However he does appear on a collectible card in Sonic Rivals 2.
Sonic Rivals happened in 2006.
Haggard
Yes, there are three: Sonic Rivals, Sonic Rivals 2, and Sonic Mega Collection.
There is no Sonic Rivals 3...yet.
Sonic Rivals was created on 2006-11-24.
Shadow the hedgehog, Sonic Riders, Sonic Riders: Zero Gravity, Sonic the hedgehog (2006), Sonic Rivals, Sonic Rivals 2, Mario and Sonic at the Olympic Games, Mario and Sonic at the Winter Olympic games, Sonic and the Secret Rings (multiplayer character) Sonic and the Black Knight (As Lancelot) and soon to be Sonic Colours on DS.
You have to unloock diferrent Cups and play Multiplayer to unlock character costumes