ok so this being a battle stance i'd like to start of with the pose first. the way that he is crouched over suggests that he may have just landed after jumping down from somewhere. the way he has his body positioned seems that he doesn't want to take his eyes off of the enemy. given knuckles personality this person is probably very powerful if knuckles is being a little wary of them. there is a strength and determination in his eyes that is very obvious but it also looks maybe a bit protective. this with the pose seems to say that he may have jumped down in front of a friend who was in danger.
the next thing i'd like to point out is the shading. whereas in your last picture sierra-windguardian.deviantart... the shading in your style was very subtle for the most of it. in your SA style however the shadows and highlights contrast the main colors. this kind of style gives it a more energetic feel with the brighter colors.
overall it was done very well and the effort that was put into this shines through.
Amazingly done! I still can't figure out how to shade like that (the International style). I haven't really tried very much, but just thinking of it makes me cringe. You did it excellent, though. Great pose and coloring, again.