This image radiates a warm aura, due to the setting sun or wildfire in the background, whichever it is. The oranges and red complement the earthy tones of the Diglett trio shown. You also managed to place the pokemon centrally, using the angles of the dugtrio to move the eye towards the center of the picture. As far as balance within the image goes, the pokemon being centralized, with the sky and ground about equal, give this image a fair amount of weight all around.
Diglett is a fairly simple pokemon. So, I’m glad you managed to get it right. Each one looks correct, yet each has its own slight differences. The colors are spot on, so not much to say there. Only think I’ll hit you on is the cartoony shadows. For images of higher rank that usually should be much smoother transitions. But it seems to fit with the general appearance of the whole image in general.
So we have what I’m going to guess is a beautiful sunset going on in the background, with clouds idly blowing by. I say guess because its honestly a little hard to tell if you were going for that, or to show destruction and power by placing a wildfire behind Diglett. Make it more obvious which route you were going for for future images, I like the look of it either way. The ground could possibly use more textures, or perhaps grass closer to the mud around Diglett. It looks surprisingly barren, unless they are on a dirt mound that cannot be seen due to scale. The blades of grass you have in the background are good, especially the multiple-colored layers to show depth. As far as shading goes, its very rough, but it is correct as per the light source that you have defined in your image.
1. Definition - try to give things like the background here a little more detail so we can make accurate assumptions about what's going on
2. Smoothing out shading, and adding additional textures when necessary
Have yourself a Diglett