Sonic Rivals/Characters

Sonic Rivals sports 4 main characters, and a secret unlockable character. All of the characters have appeared in previous sonic games. =Playable=

Sonic
Sonic is the eponymous character and the first one that the storyline says finds this island. Sonic has the special ability "Sonic Boom", activated by a special ability power up, which lets him run incredibly fast. He has defeated Eggman so many times that it's difficult to count. Sonic's motivation is that Amy and Tails have been transformed into cards, and he wishes to free them.
 * Sonic first appeared in Sonic the Hedgehog, in 1991. Sonic has three alternate costumes: Ice, Black Tie, and Leather.

Knuckles
Knuckles is the guardian of the Master Emerald and the sole inhabitant of Angel Island, a floating Island in the sky where his people once lived. He is rather naive and has been tricked by Eggman numerous times. Knuckles' special ability is Hammer Punch, much like in Sonic Adventure 2, it stuns the opponents regardless of where they are on the map. Knuckles was watching the Master Emerald one day when it suddenly disappeared, and there's only one possible explanation: Eggman. Knuckles sets out to find him and stumbles across Onyx Island, only to see Sonic. He discovers that Eggman has converted the Master Emerald into a card.
 * Knuckles first appeared in Sonic the Hedgehog 3, but his first playable appearance was in Sonic & Knuckles. He is also the only one in this game who is not a hedgehog. Knuckles has three alternate costumes: Leather, Armor, and Eggman.

Shadow
Shadow was an experiment to create the Ultimate Life Form. He was thought to have died after aiding Sonic at the end of Sonic Adventure 2, but survived and has been in almost every game since. Shadow's special ability is Chaos Control, where he slows down time for his opponent. Shadow gets a mysterious transmission from Eggman calling for help, and decides to investigate. Later he gets another message from Rouge, claiming she's discovered a secret about Eggman, and she disappears. Shadow sets out to save them and find the secret. When Eggman holds up an Eggman card, it is revealed that the real Eggman was imprisoned in a card, and this is Eggman NEGA from the future.
 * Shadow first appeared in Sonic Adventure 2. Shadow has three alternate costumes: Leather, Flame, and 80's.

Silver
Silver is a hedgehog from the future, here looking for Eggman NEGA. Silver plays a role similar to Sonic's. It is revealed to Silver by Eggman NEGA, once he has been revealed, that Onyx Island is actually Angel Island from the future, and Silver sets out to send things back. Silver's special ability is ESP, which confuses his opponents, namely messing up the controls.
 * Silver first appeared in Sonic the Hedgehog (2006). Silver has three alternate costumes: Leather, Lightning, and Christmas.

Metal Sonic
Metal Sonic is the unlockable player. He can be fought several times over the course of story mode. To unlock him, collect three Metal Sonic cards, which can be done by completing the game as all four characters. Metal Sonic can't play story mode, however he can play Challenge and Cup Circuit. He has no special ability of his own, and can only copy his opponent's.
 * Metal Sonic first appeared in Sonic CD, and does have three alternate costumes: Leather, Circuits, and Jester.

=Non-playable=

Eggman NEGA
Eggman NEGA is the villain of this game. He is from Silver's future and came back in time to take over the world and make up for his ancestor Eggman's mistakes. Only Shadow and Silver find out this truth, while Sonic and Knuckles still believe they are fighting the real Eggman.

Tails
Tails is Sonic's buddy, and runs into Eggman with him at the beginning of the game. He is turned into a card, and freed at the end of Death Yard Zone. Tails helps Sonic and Knuckles reach Meteor Base in space.

Amy Rose
Amy only appears as a card in Sonic's story, until she is released at the end. Thinking that her rescue means Sonic loves her, she pursues him, but he and tails decide to collect more cards.

Rouge
Rouge is a bat who sends a message to Shadow saying she knows the truth about Eggman. What she discovers is that the Eggman they are fighting is actually Eggman NEGA, and the real Eggman is imprisoned in a card. She becomes a card as well, and Shadow must save her.

Eggman
Unlike most Sonic games, Eggman is not the villain this time. Eggman actually helps out by giving Shadow and Silver a ride into space. He is imprisoned in a card from before the game starts, and manages to send a transmission to Shadow, initiating his story.