Here is the full list of all 20 Alexio achievements.
Collect two vinyls
Collect all vinyls
Find one golden statuette
Find all golden statuettes
Kill 50 enemies by jumping on top of them
Kill 150 enemies by jumping on top of them
Defeat 50 enemies using a stone
Defeat 100 enemies using a stone
Find all friends and have a party
Collect all arts from the pieces
Break up 10 stone guys
Visit all levels
Defeat your darkself and get the Monobrow
Be the best in the records
Type password DUCK
Watch animation in main menu and all idle animations
Complete the training level without destroying enemies
Collect 20 red coins
Try all types of hats with abilities
Unlock 10 doors with lock