Silver Sonic II was deployed to attack Station Square after it was damaged by Perfect Chaos, he was defeated by Sonic and made the city protector after being rebuilt
He later rappeared when Shadow attacked the city and fought Shadow but was defeated.
Metal Sonic
It is implied in the next issues cover that Silver Sonic II is actually just another version of Metal Sonic(Metal Sonic), though it is unlikely unless Silver Sonic somehow transferred his consious into Metal's body and another AI was placed inside his.