Synonyms to the likes of

ally, accessory, accomplice, act in concert, act together, adjunct, affiliate, alter ego, amalgamate, analogon, analogue, apply, archduchy, archdukedom, associate, band, band together, be in cahoots, be in league, bedfellow, bind, body politic, bracket, brother, brother-in-arms, buffer state, bunch, bunch up, cabal, captive nation, cement a union, centralize, chieftaincy, chieftainry, city-state, close copy, close match, club, club together, coact, coadjutor, coalesce, cognate, cohort, collaborate, collaborator, colleague, collude, colony, combine, come together, commonweal, commonwealth, companion, compatriot, compeer, complement, comrade, concert, concord, concur, confederate, confrere, congenator, congener, connect, consociate, consolidate, consort, conspire, cooperate, coordinate, correlate, correlative, correspondent, counterpart, country, county, couple, crony, do business with, domain, dominion, draw a parallel, duchy, dukedom, earldom, empery, empire, equate, equivalent, federalize, federate, fellow, fellow member, free city, friend, fuse, gang, gang up, get heads together, get together, go in partner