Visual breakdown of Scorpion versions:
Contrast: First, notice the highlight on the elbow and bicep of MK1 Scorp. This shows strong contrast, and is indicative of sunlight or other strong sources of light. Compare this to the others.. and see how much more lighter and "Flatter" they are.
Contrast really helps to make a character Pop out. Similarly, look at the underside of his raised elbow in MK1... and see how much more darker it is.. in comparison to the others. This again, shows excellent use of contrast. There isnt even any shading on the elbow of MK2s scorp.
Shading: Besides the better contrast... there is very bad shading period.. on MK2 version and beyond. You can see in MK1, that Scorps shins are much darker than his upper uniform. Thats because they are more in the shade. A lot of light is being blocked from his own body being in the way.
In MK2... his shin guards are the same color all the way through.. in fact... they are almost Brighter than his uniform (due to the checker pattern on the uniform).
Even when MK2 bends his knees.. theres almost no change in the shading of the shins. Same for the side to side motion of his uniform.
Look at the shading on the Heads and masks as well. Theres almost no shading at all on the MK2 compared to the MK1 version. No highlights. No details. Very flat.
MK3 Scorp:
In this version, he appears far darker. This makes more sense in many ways... as there is a lot of dark areas in the game (thought, I would personally use different sprite sets for that) But... the shading is still quite weak. Very flat. Pretty much no highlights at all either.
Character Shape:
Notice the bulk of Scorpion MK1. Hes a Thick beast of a fighter. Seems far more menacing and realistic to the way he fights in that game. Even so, one could say that his uniform is a little baggy. And rightly so... as uniforms are designed to be baggy.. in order to allow more flexibilty for kicks and other long movements... without any binding.
On The latter versions... he looks like a much smaller guy, with very thin legs... and or very tight pants. In fact, his pants dont even seem to move, when he moves.
Animation:
Well, i have to say that I really prefer the original side to side, circular twisting animation here.. over the other strange variants. MK2 seems to omit the side to side.. just lightly bobbing.. and his open hand... is a big no-no in real fighting. MK3 has changes him to a back and forth movement... which is more like Tae Kwan Do... and maybe a bit more realistic to how many people play... However... the way its animated seems really wrong. Almost as if some computer model was hand-animated... and it just looks so artificial.
Visual Quality just went from downhill ... each progressive generation.