Here is the full list of all 38 Sonic Superstars achievements.
Defeated 1,000 enemies.
Defeated the gold enemies in all Stages.
Collected 100 Medals from Bonus Stages.
Used Trip's double jump to defeat 100 enemies.
Cleared Zap Scrap in Frozen Base without taking damage.
Defeated the true boss.
Collected 10,000 Rings.
Collected 600 or more Rings from ACT "Fruit".
Cleared Trip's story.
Turned Lagoon City's Goal Plate into a pile of fruit.
Used Tails' aerial attack to defeat 100 enemies.
Used Amy's Hammer to defeat 100 enemies.
Used Sonic's Drop Dash to defeat 100 enemies.
Used Knuckles' glide to defeat 100 enemies.
Cleared a Stage with a friend.
Turned super using the 7 Chaos Emeralds.
Used the White Emerald power "Extra".
Used the Yellow Emerald power "Slow".
Cleared all of EGG FORTRESS.
Cleared all of FROZEN BASE.
Used the Goal Plate to reveal the hidden Item Box.
Cleared all of CYBER STATION.
Used the Green Emerald power "Ivy".
Cleared all of GOLDEN CAPITAL.
Cleared 1 Bonus Stage.
Cleared all of PRESS FACTORY.
Cleared all of SAND SANCTUARY.
Cleared all of LAGOON CITY.
Cleared all of PINBALL CARNIVAL.
Used the Light Blue Emerald power "Water".
Cleared an ACT "Fruit".
Cleared all of SKY TEMPLE.
Used the Purple Emerald power "Vision".
Cleared all of SPEED JUNGLE.
Used the Red Emerald power "Bullet".
Collected 200 or more Rings when clearing a Stage.
Cleared all of BRIDGE ISLAND.
Used the Blue Emerald power "Avatar".