Y0! I'm gonna give you my run around on these sigs! But be warned, I am going to be a harder critic than I usually am.
Alright, for this, I'm just gonna give you the run around about my favorite and least favorite one to keep it short. If you want a more detailed one on all of your sigs, just let me know. :-) My favorite one is the one that says "Love, Dreams, and Happiness". To me, it looks like it didn't take a lot of effort, but hey, if I fits and you like it, then it isn't my say. I like how it fits together as the pop culture background and a Pokemon vector. The colors don't exactly match but it looks good. Something else I noticed is those black "sparkles" to the right of the sig. They don't exactly fit into the whole scheme of the sig and they threw it off for me. Also, about the text on it. It looks like you lowered the opacity of the typography then added an outline. Of course, depending on the style of the sig, doing that with the text can look very nice but in this case, not to me. You could try to put the text in sort of a colorful base in bold letters that fit into the sig. Also, the text is a bit too obvious. You are trying to draw focus to your focal/render, not the letters.
2/5 for creativity.
My least favorite of them all is the Camarupt sig. Again, your text is way too bold and obvious. Also, the Camarupt is supposed to be the focal point of the sig, right? If I'm wrong about that then, please, let me know. Anyway, it is way too faded. It needs to be out there and sharpened, not in the background and faded. Maybe you could form the backgound images arounf him and sharpen him a bit to draw a bit more focus.
2/5...
I also noticed something about most of your sigs. They look like all you did is make a sild color layer, slap a brush on top of that, and then pop on a render. Although it looks pretty good with the Ivysaur one, it doesn't work for most. (Also, the text on the Ivysaur one is WAY to obvious.) It could also help you to learn how to use C4Ds and other effects.
Again, this is just my opinion. Let me know if you disagree with any of it. Hope I didn't offend anyone. :-)