Here is the full list of all 9 Fancy Skulls achievements.
Complete level 3
Kill 12 enemies with mannie's homing mines
Complete level 6
Complete the game once
Complete the game taking exactly one point of damage
Earn all crowns on one floor
Do not pick anything up, but a single coin and keep it to the end of the game
Stop touching the ground and kill 3 enemies without landing
Transmute 12 objects