I think a lot of what makes animated fight choreography look great is careful selection of staging.
Poses and impacts need to
look powerful, or elegant, or intriguing. Even the simplest punch can look powerful with careful staging and editing.
If you place a camera in a position so that the viewer is proverbially living in the scene where they can see the action and the power, then impacts seem much more incredible.
Ponder this scene. A floating head approaches an aluminum can, dismayed. He punches the ground, causing the can to pop up into the sky.
Here's an example of the scene with really bad staging.
http://www.youtube.com/watch?v=nDzDhNi7GI4
All the props in the scene are laid out to the audience, but do you feel any connection to what's happening. Do you even realize where the aluminum can is placed?
Here's a bit of better staging where the actors are placed more prominently in the scene. Same animation.
http://www.youtube.com/watch?v=7jxcKGEyhzk
Staging in this scene is better since you see the aluminum can up front and you see where the head is looking. When he brings his fist down, you are right there in the scene when the can pops up and you even try to follow the can. However, you lose some of the relativity of size and distance between the can and head.
Here's the staging I used in the final for this project. From just this, can you figure out what is going to happen next after the can is popped up given his pose, the position of the can, and the green bin at the right?
http://www.youtube.com/watch?v=uBsS2KFU3mQ
The thing about staging is that you want your scene to be clear, AND you want your audience to feel as if they are somewhere relevant in the scene. You don't want to have them removed from the scene unless you have a specific purpose. If the audience don't have any connection with the scene, they won't feel the power or subtlety that you are trying to convey.
You can read Brad Bird's little visual rant in composition to get a base point on where to begin.
http://www.animationmeat.com/pdf/televi ... _comps.pdf
In essence, you want to place all important actors in the scene and you want to make things look interesting. You want to lower the horizon line so that things are displayed more prominently. You want the audience to be there when the action happens.
Here's the most important thing. Your staging and composition needs to follow the action, especially in fight scenes. Once you have an opponent step into the fray, you need to make sure that all the actors are staged in such a way that you can see all the action and the action looks powerful/slick/whateveryouareworkingfor.
And some food for thought, look at this scene of a FMV made by a very big game development company.
http://www.youtube.com/watch?v=rgatL2LQ ... page#t=85s
Staging is good up until 1:38. Can you tell me what the hell just happened there? Is he feeding him? Is his arm being bitten? Is it actually dead? Do we get any anticipation when he's attacked from behind? Is there even a reason for focusing on the spine floating in mid air?
Starting at 1:38, the staging allows us to see a struggle between Zeratul and the hydralisk. However, the staging is weak in that what's happening in the struggle is entirely unclear. Clarity and power are completely lost as a result. The second hydralisk comes in at 1:40 with little anticipation, something that could have been solved with better staging. The scene cuts to the spine that had been cut off and Zeratul grabs the spine. We gain a sense of intimacy with the scene, but we lose clarity of what is going on in the next shot. Clarity and power is localized to the spine, but in doing so, we are separated from the rest of the scene in a way where we no longer have bearing in relation to Zeratul. This problem stems from a little bit of bad staging and bad editing. Zeratul and the hydralisk should have always stayed in frame so that when Zeratul finally plunges the spin into its head, you know exactly what's going to happen and you can feel the power from the strike.
This is what you have to be aware of when doing fight scenes. Things are not clear? You're dead in the water. Things don't have enough power? You're dead in the water. There are many, many things you have to be aware of, but the most important part besides motion, is staging since that is what puts your audience in the moment so they can really feel that pop.
You need to direct your audience on where to look and how to feel it or else, no matter how by the books your motion is, it'll still end up looking and feeling weak.