First, add more spots and try to make them look more like they do on the picture that lugiaisbeast101 posted.
Second, the two orbs on the sides of his branch.. hand.. arm things.. They should be closer to what would be his hand.
Lastly, make the Y on his head a tad bit thicker.
I make Sig Banners, take a look. ^^ http://www.pixelmonmod.com/forum/viewtopic.php?f=9&t=3064