As I have thought, it needs more than just /evolve in order to get it's stuff. I remember this from testing this creature long ago.
There is a list of stuff that can be gotten for the creature if you had enough points for it, I just don't remember what the list had. :/
I also remember being able to get all of it's abilities somehow if you were an admin or SA without having to get any points for them.
I do know that it is possible to have the fully evolved Kha'zix if you are not in a mini, I think it's pretty neat imo.
Also, when I did use the /evolve, it said that I had options zero. Is that a glitch or something or is is normal?