Some enemies can petrify or freeze Sonic, Knuckles, Shadow and Blaze.
When a character is petrified, there is no way to turn him/her back to normal, which means the character is considered dead and the player looses a life.
When a character is frozen solid, he/she can't move, but can break free by shaking the Wiimote. While beeing frozen, the character is very vulnerable, beeing hit by anything while frozen solid results in death.
Both statuses can be avoided by wearing certain items which make you immune to petrification/freezing.