The spikes on his back look better
Idle: The tail motion is nice, you should also animate his body & his shoulders kind of the same "wavy" way, I think it's weird if his tail moves a lot and his body remains still..
Walking: It does look like he's walking, but it looks like it's missing half of the frames, it feels like a loop of the first part of his walking animation to me. But if you really want to keep it at no more than 4 frames, I don't really know how you could improve it ^^
Other than that they look nice ! Will they be in the same game as your witch ?