In first contact picard kills a couple of borg drones in the holodeck with a holographic tommy gun. According to tng, the federation doesn't seem to know anything about these. In regeneration starfleet learns about a culture that we (as audience) know as the borg.
V'ger machine culture aliens vastly more powerful than the borg. Has this species been identified? In star trek, the borg queen is said to be from species 125.
Additionally, if the borg treated the federation and related alpha/beta powers like they did species 8472 and sent hundreds of cubes instead of just 1 each time, this answer. The borg queen states openly while interrogating data that she considers the borg's biggest weakness to be their remaining vestiges of humanity (humanoidity?),. Or has it been assimilated before the rest of the galaxy could encounter them? Well they built a machine around voyager, that took 30 minutes for enterprise to fly on impulse engines.
In ds9 itself, the borg were never involved in the plot. It would appear that while the borg are able to adapt to become.