I am still working to improve the design, and foremost of my concerns is the "it doesn't look like a fire type" issue. I don't necessarily agree with Rising Dusk that we need to be rigid about using existing ingame typing cues. Pokemon is notoriously inconsistent about visually showing typing, and when it comes to viewer opinions as to what "looks like <whatever> type", there is even more inconsistency. But I cannot dispute that Fire typing is FAR more conformant than probably any other type, and there are very few cases of fire types that do not exhibit the visual cues RD mentions. So yeah, I cannot deny that my design is bucking a clear ingame trend.
What does that mean for my design? Well, it comes down to two questions:
1) Whether I think making my design "look more like a traditional Fire type" will make the design materially "better".
2) Whether I think making my design "look more like a traditional Fire type" will get me more votes.
As to the first question, I haven't come up with anything yet that makes it more like a classic fire type that "improves" the design. But I'm still working on it, and I have a few things left to try.
As to the second question, I'm not overly concerned about the polls these days. It's a fine line to walk when playing for votes. I have no issues with tweaking a design to satisfy more people, particularly if I think my design has a real shot at winning. Not really because I want the win, but more because the winning design becomes the property of the entire community. So when I'm working on a design that I think has a real shot at coming out on top, I feel a certain obligation to bend to community opinion. When working on a more quirky design, I tend to ignore community opinion more often, because I know I'm not a real contender for the win.
It's a gray area for me. At this point, I'm keenly interested in feedback and several people have made some good suggestions. The compliments are greatly appreciated, and most of the criticisms are spot on. Making a good CAP design is a tough balancing act, as I'm sure all the artists in this thread can attest. We're all trying to make ourselves happy and everyone else happy at the same time. It's not easy. But I love the challenge!
In the case of my current design, I am trying to incorporate the fire type by visually showing "radiation". If you look up "radioactive" in Google Images, you will see a HUGE coloring trend in the results you get back (outside of the yellow-and-black triangular radiation symbols) -- "bright glowing lime green = radiation". That's why I made my design glowing lime green. Well, I made it "glowing" as much as I can within the rules of CAP design. For those of you suggesting I add an exterior glow effect to my design, you need to check the CAP rules -- external glowing effects are illegal. So for this design, while I agree that a glowing gradient effect would really hammer home the "this thing is radioactive" theme -- it would get my design disqualified. And I have no interest in trying to get around the rules in any way, because I consider that tantamount to cheating. So, an external glow effect ain't gonna happen. I've added as much internal "glow" as I think I can while remaining faithful to the general complexity of what I think can be sprited.
I was hoping people would easily connect the coloring to the concept of radiation. If the viewer makes the connection to radiation, then I feel fine about adhering to "game precedent", because I think radiation is a great "fiery concept", regardless of coloration. If people don't make the connection with radiation, then yeah, I guess that's a problem. I don't have an issue if people need it explained to them that this design is radioactive. There are many pokemon designs that needed to be explained to me before I understood them. I'm most curious if people can't see radioactivity AFTER it has been explained to them. I think the current design satisfies that basic requirement, and it just needs some tweaks to be improved.
I'm fully aware that voting polls do not have benefit of an explanation. Few voters bother to look at the full submission post. They look at the pictures and vote based on what they see in it. I am fully aware that some people will see the green and think "Grass". I'm also aware that a green pokemon with internal floating parts will invoke comparisons to Reuniclus. I've tried to get away from that by changing the coloring, but the results were not too good. Here's two alternate colorings (but I tried many, many more than just these).

One of those looks more like fire, I guess. The other looks more like poision. Neither of those looks like radiation to me. I'll fully admit that I've gotten accustomed to the glowing green, so if you think either of the above colorings looks better than the green, I'm open to hear it. I'll post more work-in-progress stuff as it develops.