Thanks for the tips! I didnt realize we had to make an attack animation xD

That doesn't look like an attack animation...

Your mushroom cop should either fire a shot from his gun or do something that at least looks like an attack. A speech bubble saying "Freeze" doesn't exactly make it an attack animation in my opinion.

Plus, your sprite could use some work. For instance, shading, especially the shading on the head and gun; it should "follow" the shape of the shaded object and the light source (your light source seems incosistent, but it looks like it's coming from the top right corner) as long as it doesn't make the piece look pillow shaded. The way you shaded it makes your piece look kinda flat in places.  You should shade the gun also because it looks really flat, and those "arm" look weird and too thin in my opinion.

A little tip: try looking at some reference images. Trust me, they can really help out 

I hope this helps.