Hmm... Just out of curiosity, why is it that the arrows point in the opposite direction of the stat that's beneficial/hindering?
For example, the blue arrow pointing up for Miltank's attack and the red arrow pointing down for its special defense. Because Miltank has a Calm nature, it would get an increase in its special defense and a decrease in its attack. This is the same with all the information sheets you have, with the exception of the Pokemon that have natures that don't effect their stats (like Metapod and Kakuna).