Here is the full list of all 53 ShineG Has Nightmares achievements.
Get Gorgeous Sapphire Crystal
Get Dark Star
Kill the 4th BOSS
Get King's Tears
Get Gorgeous Agate
Get Magister's Regalia
Get Gorgeous Aventurine feldspar
Get Inlaid with ruby skirt
Get Rebirth of blue crystal
Kill the 3rd BOSS
Get Eternal Staff
Get Cat ears
Get Inlaid with red crystal vest
Kill the 6th BOSS
Get Glowing green vest
Kill the 2nd BOSS
Get Slightly glowing green vest
Get Devil Minions
Get Dreamwalker
Kill the first BOSS
Kill the 5th BOSS
Get Wisdom Staff
Get Doom Blast
Get Primal Blessing
Get Savior's Glory
Get Inlaid with red crystal of tight clothing
Get Glowing yellow skirt
Get Glowing purple skirt
Get Inlaid with topaz skirt
Get Little Devil's Gift
Get Nightmare's Gate
Get Glowing headdress
Get Charm
Get Red Devil's Horn
Get Devil's whisper
Get Devil's Wings
Get Devil's Claw
Get Cunning crystal
Get Nightmare Horn
Get Nightmare Wings
Get Druid's Crystal
Get Nightmare Claw
Get Gorgeous Lapis Lazuli
Get Brilliant Lapis Lazuli
Get Brilliant Agate
Get Brilliant Sapphire Crystal
Get Gorgeous Ruby
Get Brilliant Ruby
Get Brilliant Aventurine feldspar
Kill the 7th BOSS
Kill the 8th BOSS
Kill the 9th BOSS
Kill the final BOSS