Countries' rhymes with:
countries, country's, countries, country's, countries, country's, descarpentries, entries, pleasantries, sentries
Countries' sounds like:
cantor's, cantors, cassandras, cemeteries, centaur's, centaurs, center's, centerre's, centers, centers', centres, centrex, centuries, century's, chandrika, chandross, cinders, cindric, comandeers, commander's, commanders, commentaries, commentator's, commentators, commenters, commodore's, commuters, comtrex, condors, condracky, condracky's, contours, contras, contras', contreras, counters, countersue, countries, country's