You never under any circumstances use paint default colors, because they are horribly bright and ugly. Use colors form other pokemon sprites. You didn't even recolor the otulines either, which is a negative. YOu need soem work on recolors.
As for the chikorita, all you did was copy/paste another leaf, and that took of some of it's head, which makes the sprite look unsightly.
I would say go for something more challenging, but you need to work more on this concept first.