Chaos Emerald

A Chaos Emerald is a powerful gem found in the Sonic the Hedgehog series. There are 7 in all, comparable to the seven relics needed in Super Mario RPG: Legend of the Seven Stars and the Paper Mario series, and once all are gathered, they turn Sonic into Super Sonic.

In Mario & Sonic at the Olympic Games, the Chaos Emerald appears in the Dream Race of the game. It acts as a rare item, that can help make a major comeback. When a player uses the Chaos Emerald, it halts every opposing player in their tracks, and stuns them for a few seconds, as well as give the user a speed boost. This allows the player to get a ahead easier. But, the effects wear off very quickly, but the opponents still have to gain speed again.

In Super Smash Bros. Brawl, the Chaos Emerald appears during Sonic's Final Smash, Super Sonic. Once the Smash Ball is broken open, the Chaos Emerald's instantly appear around Sonic, causing him to transform into Super Sonic, as mentioned above. However, the Chaos Emerald's have only been confirmed to appear during Sonic's Final Smash, and it is unknown whether or not they will appear anywhere else.