Hi
With a tank that size you may be able to keep several pairs but I would stick with one specie at least until they pair off.. They are mostly aggresive to their own kind
and tend to leave other fish alone except when spawning.lol
tetras and corys need to be kept in groups of at least 6 each more is better. They will probably eat the newborn guppies but a good source of live food.
Blue rams are one of my favorite fish!!! gary