It might be kind of cool if you play around more with giving them distinct shapes-- that's another important thing with the characters in TF2 actually, they all have strong silhouettes. Just as an example, you could try to make the scout skinnier, and the engie + soldier a bit beefier.
I kind of like the 2-frame animation actually, it's cute! Reminds me of Cave Story c:
I kind of like the 2-frame animation actually, it's cute! Reminds me of Cave Story c: