Here's a 4-frame jet exhaust animation, a 4-frame 16x16 flip jump, shooting straight up and a megaman-style slide just for good measure.
All tops are compatible with all bottoms -except- looking straight up and crouching. I doubt with normal controls, you'd be doing that anyhow.
Also, I took the liberty of some redesigns of your aliens. Wasn't sure of tile restriction, so with the exception of the spy, I gave them each a simple 2-frame, full tile animation. As named on your site, there's the spy, pupple, glug, miglaf, and golmar.