The things that would necessarily be true would be that, they would have superior weapons and tech, they would both arrive and reveal their presence (generally)

The things that would necessarily be true would be that, they would have superior weapons and tech, they would both arrive and reveal their presence (generally) on purpose, the outcomes are pretty binary where it's either to elevate our species or suppress it, they are somewhat like us (as to huge ones we might as well be bacteria, and to microscopic ones, we're monsters) and there would need to be some condition they were waiting for that made revealing themselves both economical and necessary. Mere benevolent altruism doesn't justify the energy costs to travel space, there has to be something else they need from us. The discipline that has the most predictive power about their intentions is likely economics. Maybe they want to use us as an expendable species of space-apes for further colonization of new planets. It's an upgrade the same way being a research chimp is an upgrade. However, given the time/distance they've traveled they'd be adapted for space faring, and not planet dwelling, so in terms of their deficits, muscles developed under gravity aren't their specialty. Their bodies would be the absolute minimum necessary to contain and sustain their minds, reproduce, and operate their tech, to where what we encounter or perceive would likely be exoskeletons. What minerals are unique to a planet like ours (other than life) that can't be found with less hassle than getting here, elsewere in the universe? What should we do? Listen. Learn. Then negotiate. They need us for something, and anything less than the fairest possible terms is going to be very bad for our species.