The Gardens Between

This Achievement is found in World 7, level 2 or 7-2 for short. This is the musical level with the pair of headphones in the icon. You will need to find the hidden box character behind a purple cloud wall.

Once you start the level, go forward and wait by the first cloud wall until the golden box lands on the other side of it and opens it, then run through. Repeat this again to get your friend in. Once you are both in, move forward and have your friend activate the bell to open the darkness pod, then approach it and have it steal your light. Move up to the radio and you'll have three colored boxes and three strips that match them on the radio. While on the golden strip, wait for the golden box to get to the highest platform then move over to the blue strip. Wait for the blue box to land next to you then run over to it and drop your lantern on it. Move back onto the blue strip and wait for the blue box to land next to the golden box and absorb the light. Move the blue box to the lowest island and move over to the red strip. Have the red box move over just one island, then move back to the blue strip. Wait for the blue box to jump over to you, and take the light from it. Backtrack a short distance to where there is a purple cloud in the wall and uncover it to find the hidden box and get the Achievement.

This sounds like a lot of complex work, but just watch my video below for easy reference.

Level 7-2 (the pair of headphones).

Complete the radio puzzle to get the light, then backtrack to remove a fog wall.

here is a video of me getting the achievement i hope it helps you out