How do i allow other physical forms to other nations?

[Gandalf Parker]

It can be done using map commands so that it only happens when playing that one map. You can give yourself any units in the game, or anything as a god (harbringer, horror, iron dragon, or a dragonfly if you wanted it).

Or you can do it with a mod such as the one you named. Just grab one and look at how they did it. Change whatever you want.