I am the Borg
My fave race, so much so i struggle as any other race due to no assimilation or rapid transport system.
In a no frills game i am in, the borg appear unbeatable... but that is never the case.
1 as stated hit the fireclouds, and if your a cloaking race its easier. No chunnel if towed and you tow them to their death.
2 strip every planet in front of them including clans
3 ally with everyone else and hit them on multiple fronts. Smaller races should just keep minefields up, crystals should hammer out the webs
4 it is foolish for smaller races to take them head on, all you do is give them priority build points and more annis and bios appear on your radar
5 strip and run, or make every planet a starbase thats fully loaded.
You need team work, you need to frustrate the hell out of them and you need to stay out of range of the cubes. As the borg, i smash my way though other races, throw caution to the wind as there is bugger all that can stand up to the cubes. And with the borg economy most bases will have cubes ready to build.
Of course it goes without saying, if the game you are talking about has me as the borg, then just quietly surrender everything to me