Hm, well, I have to agree with others that your actual spriting needs some work. But don't get discouraged -- you just started and even the best pixel artists have room for improvement!
I've never been huge on fusions myself, but you have a few good ideas. I think especially when you are just starting out, try to stick to Pokemon with similar body structures. Then work on making your fusions as smooth as possible. Take your "Mightyzoon" for example. Make sure you keep your outlines visible! Unless you are working on a Missingo or another glitch Pokemon, clean lines are very important to smoother sprites.
Instead of mashing every part of the Pokemon together, pick a few things (such as Zigzagoon's fur and colour scheme), and work on transferring them to the second sprite (Mightyena). You can recolour the legs instead of trying to paint and paste over them, and it will look much more natural; and Mightyena already has a mane for you to work with, so try to make Zig's fur fit in with its flow. The last thing I'll mention for now is remember to pick which colours you want to transfer where ahead of time -- making a colour pallet from each sprite will give you an idea of how they match up.
On a final note -- please crop your images! The overall size is so much larger than the sprite itself and it's very distracting. And most people know how to find a list of Pokemon sprites, so I think including that sheet takes up some valuable first-post space in your topic.
Sorry if this seems overwhelming! You do have some interesting ideas, so keep it up! Everyone started somewhere. =)