When you are playing Sonic's action stages and Tails is on the screen, a second player can control Tails with a second controller. Any rings Tails collects will be added to Sonic's totals. Be careful to not make Tails break open any shields, invincibilities or One Up item boxes as those will not be added to Sonic and will be wasted.

This feature may seem trivial to most people, but you'd be surprised how much fun it can be trying to outrun player one (who's playing Sonic) when you're controlling Tails.