Here is the full list of all 14 Pulstario achievements.
Beat Secret Level 1
Ride the circle nonstop for 30 seconds
Beat Secret Level 4
Beat a level in under 45 seconds in Level Select Mode
Beat a level in Level Select Mode without dying
Complete the Game
Beat a level in Level Select Mode without using Slow Motion
Beat the Main Game in under 10 Minutes
Find the 10 hidden souls.
Make your way through the Gate
Complete each main stage in YOLO mode
Beat Secret Level 2
Beat Secret Level 3
Beat Secret Level 5