In this image, 28 colors are used, not 16 colors.
Also, the coordinates of the position of eyes and mouth are not multiples of 8.
Therefore, it can not be used.
In GBAFE, it is necessary to draw in 16 colors.
Also, if possible, the first palette should be the background color.
This image counts from 0, and the 7th color is the background color.
And the X coordinate of the position of the eye and mouth parts should be a multiple of 8.
For example, in this image, the X coordinate of the eye part position is around 20 dots.
Since 20 is not a multiple of 8, it can not be used.