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