Sonic the Hedgehog dodges the shower of tiny Robotnik bombs that rain down from above at the start, and then the Smiley Bomb appears. The Smiley Bomb hovers around overhead and attacks by flying over Sonic's position and dropping a bomb. Immediately following the explosive drop, the Smiley lowers down to attack head-on at the point of impact. After 10 hits, the bottom half of the bomb disappears leaving only the grinning head floating around in the air. The head attacks in the same general pattern, except rather than dropping a bomb, it vomits up a laser blast that splits into two smaller charges upon hitting the ground. It takes 10 more hits (a total of 20) to pop the Smiley Bomb.
The boss relinquishes a Chaos Emerald upon being destroyed and Sonic picks up another in the ensuing end sequence, dropped by Robotnik as he runs away, thus ending the game.