First of all you should add more
anticipation for each action/movement.
Why ? Because it just looks weird, the first punch, uppercut, it should be pretty powerful, thats why the screen shakes, it tells the audience "hey watchout, he's hitting him really hard" but the movement wasnt and hard/strong/powerful-looking and why ? Because you didnt put enough
anticipation and
easing in it,
example:
http://www.truploader.com/view/921348
(This animation was created today, Im not here to steal your attention I just want to show-how, k ? :D)
The next thing I'd like point out is how people actually animate, if I know there are two ways how to "inbetween".
First way is really simply and a lot of people use that, I used to use it too, but now Im using trully fbf style, the first style is called "pose to pose" animating and why am I talking about it.When someone crouches (like the black guy in your animation) he shouldn't just stop, he should move all the time just a lil bit, you can use "Free transform tool" to make it look more
fluid, but if I were you I'd redraw every frame, maybe let him stop for like 1-2 frames but not more, believe me, it looks wayyyy better when you do these
fluid movements.
Okay, we're moving on to another thing, the kick when he flips.What was wrong here..He jumps, he flips a lil bit, he kicks and then hes kinda floating in the air, then he flips and hes landing again.It was kinda awkward, you know, people really dont move like that, even stickfigures dont.How would I solve this situation.
Prepare for the jump (crouch) jump ! half flip, kicking, but still flipping and going up in the air, now he would stop for in the air (1-2 frames) the gravity starts to force him down, but hes still flipping/rotating, the he should go down and finish the flip.It should be one smooth/fluid movement.
Next thing, the reaction of the purple guy.
He's falling down, he gets hit by the attacker, on first frame the only part that should be affected by the kick should be the chest/stomach, the legs should still be straight.Next frame, he shouldnt stay on the same place in the air.. his legs should move now.3rd frame, going away from the screen,4th frame, still going away,5th should be away.Thats how would I do that.
And the last thing, arms go down too quickly, its just one frame, boom, their down, did you really wanted it to look like he's punching down ? If no, add more frames and let it look less-powerful.
Oh, another tip, let the sticks for like 10-20 frames just stare at each other before they start to move, its less-confusing =)
Thats everything I have, I think :)