These achievements are unlocked on the "Craze songs" in story mode. In order to unlock the song, you will need to get a certain number of stars in the decade as well as passing the 4 hidden moves. You can try the songs with the hidden moves as many times as you need. After that, decipher the craze and play the full routine. Since the craze is the main routine of the song, you will have seen it before and shouldn't have too much difficulty getting 5 stars on the song.
Can be done on any difficulty.