I know I'm not a "professional" with emotes, but I'll try and do my best XD)
Wow, just... wow. This is one of the best emoticon sets I have ever seen.
I just love the many faces and colours you included. The palettes are brilliant, too - bright yet muted enough so they don't take away the expression. The shading is awesome too, enough but not too many shades. Just perfect.
What I would suggest working on is making everything a bit smoother. Since the shading is already so smooth and most of the faces are too, there are still a few faces that look a bit jagged (like AI or G1). I know pixel art is supposed to have hard edges and stuff, I just think it works better with the overall look of the emotes.
But all in all, you've done a wonderful job! I can imagine this took hours to do, and I really respect you for being able to do something like this. Great job
I completely agree with you on the smoothness of some of the expressions, especially on A1, or :V, mainly because I never properly added facial expression shading to that one.
Now that you mention it, I think I'm probably gonna take some time to smoothen up especially that particular emote in the pack.
Thanks a lot for your critique!