The Mexican and Central American livebearers are all fairly compatible with each other. Most of the common aquarium strains of livebearers are Mexican or from very nearby areas of Central America. Other than extreme size differences they all get along fine. Obviously a 5 inch Poecilia verifera will not work well with a 3/4 inch Heterandria formosa, male or otherwise, but if you use a modicum of common sense all common livebearers will co-exist just fine.