Hello Fidsah, here's some advice, and an edit to help explain.
Before I get to technique, I want to talk about actual design. Monster designs work wonderfully when they borrow from nature. Invented anatomy and design only goes so far, you need a basis in reality to be able to convey that a specific character exists within a believable space. In the instance of your zombunny, there was a lot of invention going on. Some of it works, and some of it doesn't. Generally when people conceptualize new creatures they stick to what would work within reality, at least to a degree. The legs of your creature are, as far as the light conveys, blobs, maybe wheels. The mouth is a collection of teeth with no real anchoring to the face. The top of the head reminds me of sonic the hedgehog. With my edit, I'm not saying that you should get rid of any of these, but maybe make it a bit more believable by defining muscle groups which connect the parts, and unify the creature so that it doesn't look as mismatched. An understanding of basic anatomy, or even just human anatomy can help, as we are mammals and many of our parts match up.
What I changed, design-wise, was just to nudge it back towards reality. The teeth you had, although they have potential to be very cool, did not remind me of a rabbit. I remember rabbits as having very large incisors. These would not work with the kind of teeth you put on the creature, as they all need to be uniform. After I added the incisors, I decided it would be best to add a mouth of some sort. To further the idea that this is a scary monster, I made the smaller, invented, lower teeth jut out. From knowledge of human anatomy, I added a cheek. I remembered rabbits had triangular noses, so I put one on. I kept the sonic spikes because I felt they worked well. I added a tail to further it in the direction of a rabbit. The eye benefited from the addition of a visible eyelid. Finally, I added legs and feet, because having the two separate helps eradicate the blob issue you had going on.
Concerning your drawing technique, it seemed like you were highlighting the outline, as opposed to highlighting the actual form of the creature. This resulted in it looking flat, and at times embossed. I decided that the rabbit would be better off without highlights, so to speak so you could equate how I rendered it with subtracting the shadows as opposed to adding highlights. Often it works better to sculpt with the darker tones. It helped convey the creature's depth by making the face 3/4, which was accomplished by shifting the center of the mouth over from where you had it, and adding some of the other eye along the left side of the face. It's not all the angle though, most of it is the actual rendering, as a completely side view character could look just as 3d.
As far as pixel technique, your greens were all of the same hue. It helps to make things more visually compelling in this case to have bluer shadows, or yellower highlights. (although I think I did the opposite) There was a color you used to shade the teeth which was entirely invisible from 1x. With pixel art you should try to make your sprites as readable as possible, and you get that through solid transitions and well defined shapes. Your reds are extremely saturated and as a result it's hard differentiating one from the other.
Sorry if I sounded like an unfriendly robot, this was more or less a giant list *o*
this character is really neat, I hope you decide to take what I said about unity into mind when you work on the teeth. I couldn't think of a solution at the moment so I used plain rabbit teeth, but if you find a way to make them believable, go for it. You don't have to go as realistic as I did, heck a lot of the leg anatomy on my edit is invented, but please keep what I said about borrowing from nature in mind! : D
