I don't have my Epirus book here at hand, but I do believe the epeirote government (some sort of assembly or council of the tribes) voted to vest power in Pyrrhus and approved his son as successor when he died. It certainly wasn't strictly speaking a democracy, but it was closer to one than any of the other Hellenistic monarchies (maks, ptolies, seleuks, baktria). I don't have anything to check this with for the time being, but someone else might be able to provide more details.