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