The Plasm looks cool but it only has walking and idle animations. The other aliens on the other hand have a lot of animations.
Unfortunately I'm not too adept at unreal as of yet so I couldn't say, I've only been able to look at them through the mesh viewer or in a test map. The test map called "!EggPod_test1.dnf" has these aliens in it excluding the Tesla Raptor. They don't have much AI to them in the test map though.