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