I don't like military super nations strongarming the rest, either.
What's the point?
Take my Morte Empire as an example. People were concerned over my fleet but in reality my nation only wanted a new living space and perhaps alliance with other, better established nations. I was a minor power even if I had considerable military.
A nation which builds up a huge fleet and conquers everything only really works for a 4X game or perhaps a badly written fiction. Conquest is more than just killing the enemy soldiers and then painting your flag over the territory.

Anyways, if I join this game I'd do that with an alternate version of White Corps.
It's an interstellar megacorp which may be present in many of your worlds. It isn't really a nation so there are a number of unique dynamics going on.