Bit of an excuse, but I do want to keep them in the same general pose for consistency, but for the future I'll definitely differentiate the poses a bit more.

I think you can work with other elements rather than pose to get a consistency. Like colour, which you've already done. Like said before there are a lot of "bad" shading and colours that aren't effective.

Also using keeping the style as an excuse won't get you anywhere. There are issues that are non style related to both of the versions.
One of these are the anatomy. Even if you can go far regarding this for style there has to be some limit before the character just look weird and non believable. Like said before the proportions of the body just looks so off that you can't excuse it as style.
Another concern is the colours. I think you can try to be more creative with how you think with colours and take it up a notch. Dare play around with palette a bit. There's so much grey and white going on that it just makes the characters uninteresting. So in my brain there aren't really a big difference between the two different styles you've served. They give the same reaction.

I take it as you want to go for a sort of anime look for your ordinary style, here's my take on it:



Also, I have as a thing to avoid using the colour I use for outlines inside the sprite as much as possible or at least keep them seperated.

Hope it helps you on your way!

Yeah, don't pay any mind to the squarish pixels. Was in a hurry and only roughed things down with a larger brush. I think Zlym will refine the squarish forms in the background as he goes as well. It was just an edit to show an alternative direction.

This looks pretty nice!

I don't think the light to the right is ment to be the moon, but more of a lantern sort of thing?
I think the right sides looks good and gives a nice contrast to the left. What's missing and making it look a bit weird is that it got no background.
I would suggest that either the lantern on the right casts som light on the ground a bit further back, reavealing some foliage perhaps. Or imagine  windows
or a porch in the back that casts some light to the background. Any would work and give balance.

So far good work =) Really like the colours

Dithering is basically just used when you have a color restriction, or like Probo said, for a personal challenge or style. However, like people here said, it tends to look pretty bad for a trained eye
when you don't really know what it is used for. It's basically for blending two colours together to eliminate some size to the image file, by creating a third colour for example by blending two colours together, or make a nice gradient with minimal amount of colours used.

Here's a good tutorial:
http://www.spriteland.com/tutorials/pixel-art-dithering-tutorial-what-is-dithering.html]]http://www.spriteland.com/tutorials/pixel-art-dithering-tutorial-what-is-dithering.html

You've basically not given us anything but a conceptart of Mysterio? I think you should probably have some conceptart made for the actual character you'll be using.
There are plenty of isometric pixelart games and you shouldn't have a problem just googling it and find some sort of isometric reference.

I don't mean to be rude(If you are serious about creating a game), but you can't ask anyone to help you out of you don't even post any sort of work you have done. This part of the forum is for posting you pixelart and recieve feedback, not asking for help without presenting any sort of work related to the actual sprite you are looking to get help with. We are not the concept artists, we are merely here to help you improve, not create things for you.

You often get a better character if you do some pre-work, concept art, writing something about the character/short biography, what type of person it is, what clothes are appropriate for his mission. etc.

Here are some references: