I would suggest using a good tutorial. Your shading is flat, your lines are jagged and flat black, and quite frankly, the concepts are uninteresting (to me, anyway).
Chesu's got a good tutorial you should look at. If you already have, then try using real sprites as reference points (and I don't mean stealing parts and making it a fusion, I mean to give you something to look at).
Then possibly you can start by drawing up some concepts first before spriting them. You need better palette choices and more contrast for your sprites. Most of the sprites for the lineart is jagged and there are unnecessary pixels. Like blackmoonflower said, I suggest you to look at Chesu's wonderful tutorial.
It's not completely bad for a beginner i'm assuming. I'm glad you know the dithering effect as well.
If you are new, then they are OK, but if you are not, then no. Like everyone else said, look at Chesu's tutorial. Or, you could search on google about scratch spriting tutorials.
I would hate to use them in a game for a few reasons, they are incredibly flat and have barely enough shading, if enough. Then the outlines are jagged and not shaded which make them worse than before. Like blackmoonflower said, the concepts are not that good and very boring. If you really can't think of anything, get on Deviant Art and look for some concepts drawn out, and get the owner's permission to use the concepts.
You know the dithering effect, that's for starts. If you get the idea of fakemon, and think that it's not just drawing random parts and calling it a fakemon, then you are on the right path. But don't think I'm bragging about being good at it, I even used to be like you, new, and wanting to jump right in on making sprites, but I soon learned that I needed to improve, and listening to what other people had to say is what got me to the level I am on today, and soon you will be here to with lots of practice, patience, and willingness to learn from what people tell you.
You completely ignored Logeidan's post, the outlines are still more than one pixel thick and it doesn't even look like a tadpole. Also, the colours are horrible and the shading is very flat. And honestly, even if it's your first time spriting, they're still not good, so don't use that as an excuse, I've seen people come up with amazing sprites there first time.
Really you need to start straight from the bottom.
Take official Pokémon sprites and experiment with them, keeping in mind how the lines are drawn, how colour is used to make features stand out from each other and how shading is applied with regards to a consistent and universal light source.
You STILL need to look at some tutorials. I hate to break it to you, but those are horrible. The views are not correct, as in they are supposed to be facing in the same way as the sprite altaria has shown. The shading is horrible, I can't define the correct view from which the light is coming from. "Dragon Thing" does not have the correct viewpoint, incorrect shading, AND still has jagged lines. You need to use concepts, DON'T go from memory as it tends to look bad. The trainer is VERY bad, it looks bad because of the lines and the way they look jaggedy. It also has incorrect viewpoint, worst shading, and looks like it was made by a four-year old.
These shouldn't be public, because no one would use them.
C'mon guys, no need to be so harsh... He's trying, right? It's better than creating just one sprite, being proud of it, and posting it everywhere. Also, we've all been there; take a look at one of my first sprites:
Pokemonatoms, as a few people have said, you might want to try playing around with official sprites. It doesn't really matter what you do, be it fusions, amalgamations, or just small edits... Anything that involves you playing with the sprites up close will help you to become familiar with the conventions of the official style. You can keep making sprites from scratch, of course, and while you WILL improve by doing so, it won't be nearly as effective. I can't recommend playing around with the official sprites enough, as it's how I learned to sprite Pokemon. Thanks to that learning experience, I'm able to draw things like this:
Now, whether my version of the dragon thing is "better" than yours is debatable, artistic merit being what it is, but mine definitely adheres to the Pokemon style more. Aside from the fail shading because I didn't want to spend a lot of time on something that will never be seen outside of this thread.
Yes, he was being polite, but how about taking on board some of his critisism as well?
You'll never learn if you never try and take on critisism and use it. We aren't here to insult you, we're here to help you. As for the concepts, do you think Pokémon would've sold so much if Bulbasaur was just a dinosaur? No, you need specific ideas to merge together to make it a Pokémon. It is a pretty tricky process, I know from experience.
There are basically two types of Pokemon design: colorful animals, and "what the heck is THAT?"
Oh, and just to clarify, I think Ice meant a more clear concept. Instead of "dragon", maybe "grass-type dragon made mostly of wood, with horns and wings replaced with bamboo shoots and willow trees" or something. Most people will sketch out a larger piece of concept art before starting on the sprite.