Mizt, I'll rate your current one, because it looks a lot better than the Rayquaza one IMO, and also your other brown-ish one.
On your current banner... Well, good usage of gradient. Very nice. What's not so great is that it's somewhat obvious you didn't render the palkia image due to some of the splatters cutting off abruptly, and others looking as though they have a white overlay on them. I don't know if you noticed. xD The two splatters that are repeated in the middle, the big ones, that's a big no-no. You never want to use the same brushes in two places where they'll instantly be recognized as the same. That's bad bad bad, because looking as this banner, I see that you used maybe three brushes max. The text is great, though if you wanted, it could be a little bigger. Placement is alright, though you might want to shove it into the corner a bit more. The squares next to the text are a great touch. Though, perhaps next time, you'll want to make the stock a little bigger, so that it takes up more space. It's a good banner overall though, that's for sure.
If you don't know how to render on Photoshop, I have a quick and crappy tutorial I whipped up for Chikara awhile back. If you can understand it, you should give it a shot. xD You might not be able to understand it though, because I'm terrible at explaining, let alone tutorials. </3
Extremely Vague Rendering Tutorial
That said, I'll ignore the terrible render job on the next one I'm rating. First thing I have to say, there is such thing as over-use. Here, you've majorly overused the star brush, and that goes for your Rayquaza banner as well. You should try experimenting with other borders, instead of just using the dotted border all the time. Sometimes, a simple 1 px black line works wonders as a great border. *nod* The color effects on the render are somewhat odd, and I'm not a huge fan of it. But I'll have to disagree with Shika-kun here and say that the text decorations on the bottom aren't all too bad. Adding the X's, which I'd imagine are meant to be text decorations in themselves, it might be a bit too much, but if we see the X's merely as text, then it's a good attempt. Keep an eye on making sure you don't overuse a single element in your banner, because we want to see different styles. ^^
Shika-kun; Well, it's a clean render, which is good. The blending attempt on the right doesn't look all too great, but it's not too noticeable, and it's not terrible either. The background's grungy look doesn't really fit the cleanliness of the render to me though. The lines could have a lowered opacity, along with the text. Text placement and decor's are good though, font is okay. The c4d is nicely placed, so that's definitely a plus. Overall good job on this one, I'd say.
Hazuki; TEPPO PEPPER?! Can't rate it until you give Teppo proper credit. ;< Goes hand-in-hand with my dA art policy. It's technically a form of art theft to me. *having been busted for it a long time ago, I'm terribly paranoid about it now.*