Achieving an S-Rank on every act is the ultimate challenge for any Sonic Rush player. S-Ranks are awarded based on a combination of factors: your completion time, the number of rings collected, and your score. While all three contribute, time is often the most critical factor. To get an S-Rank, you need to complete the act as quickly as possible, ideally under the target time (which varies per act but is usually around 1:00-1:30). This means finding the most efficient routes, utilizing your Boost Gauge effectively, and minimizing any stops or collisions.
Secondly, collecting a high number of rings is important. Aim for at least 200-300 rings per act, though more is always better. Rings also contribute to your score, as does defeating enemies. Try to maintain your combo by chaining Homing Attacks/Burst Dashes. Practice is key; replay acts multiple times, experimenting with different paths and boosting strategies. Watch speedrun videos for inspiration and learn advanced techniques. Mastering S-Ranks will significantly improve your overall gameplay and understanding of the level design.