Ethopia, Australia, Habsburg and Zulu don't do anything at all.
Peru doesn't seem to function properly (they don't gather resources, only receive shipments). Egypt doesn't age up..
Brazil, Argentine, Chileans, Paraguay and Colombia seem to work but are inferior to the original A.I.'s.
Romania, Serbians, Bulgarians and Greeks stop after building 3 houses. You can ask them for resources however.
Mapuche doesn't seem to use their Explorer units, but seems to function.