I was having trouble with the guys with 10 billion health and damage
Are those the ones with the big welding masks that you meet at the runup t the Erchius Horror?
Like all of the enemies on that mission, they do not jump at all.
So, you can always run back to a drop-down and jump onto it. They'll stand underneath completely still and you can just slowly shoot them to death. And unlike the regular flesh monster things, they don't have a ranged attack.
I actually found that mission to be pretty easy until the boss, where I then entered the room, lasers hit me immediately and took me down to about 1 third health (I was fully rested), and then just trying to get away so I could bandage, I took fall damage because of the stupid way that you will drop down through all platforms if you don't let go of the down button.
I was in the room for about 5 seconds, then died. Didn't even fire my gun. :/
And to top it off, you have to respawn on your ship. I don't know if that means I have to repeat the entire mission, but I assume it does.