Superregionals' rhymes with:
superregionals, superregionals, regionals, superregionals, regionals, superregionals, originals, regionals, superregionals, arsenals, biphenyls, cardinal's, cardinals, confessionals, criminal's, criminals, criminals', diagonals, international's, internationals, juvenile's, juveniles, multinationals, national's, nationals, nonprofessionals, originals, professionals, professionals', regionals, sentinels, superregionals, terminals