I also agree with lagamuffin.
Firstly, the colouring isn't great. You colour outside the line in some parts and it's full of gaps everywhere. The aura (or whatever it is) is poorly drawn with the spikes going out in different directions and are all completely different sizes. There's no shading which makes the drawing look very flat.
Finally, it's hardly the hardest thing to draw. It's a circle with a background. Why not do the pokéball after it's just been thrown with the trainer doing a throwing motion in the background? Or draw the pokéball opening up with a pokémon coming out to battle another one?