PS. This is my first writing a critique so here goes nothing.
Vision: The picture is well done. It catches attention but next time, the bg should be toned down a bit to make the characters stand out even more. Sure, colorful pictures are pretty but don't put all the colors in the book in one picture. Sometimes, simplicity is beautiful so reduce the use of too much PS brushes.
Originality: The poses are nice and interesting as they really show off action which keeps the picture lively. Though I have spotted a few anatomy errors like Blue's right pointer finger, Emerald's left eye is a bit off, Platina's left hand seems not right for me, same with Pearl's left hand. Silver's legs weirdly disappeared, same with Red's knees and Platina and Dia's legs. Also, Crys' foot does not seem to be in the right angle. Still, you got everyone's character right through their facial expression and this is done with a mouse alone so you're getting a huge thumbs up.
Technique: I see you have changed the way you color and shade the hair and I love this technique better as most of the highlights and shadows are placed in the right spots. Cell shading is a great deal for you! Another plus point for doing this with a mouse alone. I have never seen anyone pull something like this with a mouse before.
Impact: Overall, this is well done and deserves attention. After all, this is done with hard work and patience. I love people who work hard but don't play around with your work too much. Overdecorated stuff is not pretty like how too much colors and PS brushes stand out more than the Pokedex. I almost did not notice that.