I saw a post that suggested that there be small premature civilizations in ES and it gave me the idea of mercenaries. Mercenaries would be only be hired by other races that you are allied and the weapons on the ships would be the current updates from the other race at that time. The types of ships the player would have access to in mercenaries would be the ships avaliable to that race and depending on your relationship with that race would depend on your avaliability to those ships. As to obtain those ships, you would have to obtain them through diplomacy, such as basically asking or signing some sort of treaty that gives you access to those ships. This might or not require you unlocking these ships, plus to give a give an advantage as mercenaries is that they would be cheaper than ordinary ships that you would build.

I really like this idea. Also maybe even add an imperialistic thing as well where you gain access to these mercenaries by taking over certain planets?

Maybe, sounds more like a conscription rather than using mercenaries thou, but hey that is a very unique way in using the local population of a captured planet. I can see that quiet useful in holding down a planet from enemy attack and using the your main fleets to keep on attacking.

This is a good idea touching on some games where you do meet strange new worlds and civilisations to interact with. Already we see the "Friendly Natives" Anomoly, this would be expanding that feature forward into something that would definitely put the E into Explore as well as the E in Exploit, well depending on what race you were, it could well be E for Exterminate! Exterminate!...