Oh wow! Nice job with these, they look great! I'm no graphics designer, but I can give you a few pointers in terms of aesthetics? Your first avatar with the Growlithe has really nice colors, but the light in the top left is pretty distracting and draws my eyes away from what I take to be the intended centerpiece. Muting the light or even tinging it yellow or orange would probably help that. The last avatar with Mario also has a nice color scheme, but I feel like it gets too dark too fast there at the bottom. The other two look great in terms of lighting, though Again I'm not a professional so I may be misunderstanding some unspoken graphics design rules.
Nice job on your avatars. Here's my thoughts on them: - I prefer to use only part of the render. You've done that well, only thing I would say is maybe make the Pikachu and Mario renders a bit larger. The reasoning behind this is, you don't want a square version of your signature, an avatar is different which is why people don't use the full render or even 75% of it instead, they use a about half or so. Besides that, these are amazing avatars and I can't wait to see more.
