Capture pokem... I mean capture aliens could be able to evolve? I mean after sure battles and train and time they could grow and gain new abilities...
This isn't pokemon, this is Poke them into a casing. Maybe they will have some kind of thing increase or depending your armor and weapon you used....maybe...just maybe.
My apologies for advance http://img1.joyreactor.com/pics/post/full/comics-JaGo-evolution-religion-596789.jpeg