Here is the full list of all 13 NiGHTS Into Dreams achievements.
Clear Spring Valley (Christmas).
Try to Paraloop all of Gillwing’s tail in one hit.
Clear all stages with a score of Rank A.
Clear Twin Seeds in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Show your supreme skill by achieving the highest Acrobat Time rating, "DREAMY".
Clear Stick Canyon in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Clear Soft Museum in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Clear Frozen Bell in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Try to guide the lost car in the Mystic Forest to the garage.
Clear Mystic Forest in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Make a Nightopian and a Nightmaren have a hybrid offspring.
Clear Spring Valley in either BRAND NEW DREAMS or SEGA SATURN DREAMS.
Clear Splash Garden in either BRAND NEW DREAMS or SEGA SATURN DREAMS.