Here is the full list of all 26 Just Shapes Beats achievements.
Get 25000 Beat Points
Rescue 250 friends (Challenge mode)
Get 7500 Beat Points
Complete 100 challenges
Obtain 15 Rank S
Obtain Rank S without dashing
Complete 50 challenges
Rescue 50 friends (Challenge mode)
Complete a challenge with Rank A or higher on all levels
Obtain 20 Rank A
Dash 2500 times (Challenge mode)
Get 2000 Beat Points
Complete 25 challenges
Dash 1000 times (Challenge mode)
Complete a playlist of 10 songs or more
Obtain 10 Rank A
Complete a level without dashing (Challenge mode)
Obtain 10 Rank B
Complete a playlist of all bosses
Complete Story
Beat 'Final Boss' (Story mode)
Beat 'Close To Me' Boss (Story mode)
Beat 'Lycanthropy' Boss (Story mode)
Beat 'Barracuda' Boss (Story mode)
Beat 'New Game' Boss (Story mode)
Beat tutorial Boss (Story mode)