Full list of all 42 Cuphead achievements. It takes around 15-20 hours to unlock all of the achievements in the base game on Windows.
The base game contains 28 achievements, and there is 1 DLC pack containing 14 achievements.
Obtain an A-Rank or higher on all bosses in Inkwell Isle II
Obtain an A-Rank or higher on all bosses in Inkwell Isle III
Complete the game on Expert
Defeat a boss using only the mini-plane bullets
Complete all levels without killing an enemy
Obtain an A-Rank or higher on all bosses in Inkwell Isle I
Get an S-Rank
Complete the game on Normal
Defeat the Devil
Obtain an A-Rank or higher on all bosses in Inkwell Hell
Buy everything in Porkrind's Shop
Get every coin in the game
Parry five times before hitting the ground
Give in to the Devil
Complete the Casino
Defeat every boss in Inkwell Isle III
Get every coin in all of the levels
Obtain all Super Arts
Defeat every boss in Inkwell Isle II
Complete 100 parries
Complete a level without getting hit
Find a shortcut
Defeat a boss with a Super Art
Defeat every boss in Inkwell Isle I
Complete 20 parries
Defeat a boss
Defeat a boss with an Extra Special move
Defeat every boss in Inkwell Isle IV
Obtain an A-Rank or Higher on all bosses in Inkwell Isle IV
Defeat a boss with Ms. Chalice
Defeat 10 bosses with Ms. Chalice
Defeat a boss with one of Ms. Chalice's Super Arts
Defeat a boss with one of Porkrind's new weapons
Defeat all of the King of Games' Champions
Defeat the King's Gauntlet
Complete your quest on Inkwell Isle IV
Get an S-Rank on a stage of Inkwell Isle IV
Defeat a boss on Inkwell Isle IV without killing any of its minions
Have 9HP at one time