The Borg vs. The Xenomorphs (Aliens)
What's to say? These are two intergalactic species that really deserve each other.
Starting conditions:
The Borg are on their Cube ship floating around the cosmos and stumble upon "a ship" (a hypothetical ship not necessarily from any of the movies) that has been overrun by facehuggers and, thus, producing a horde of humanoid xenomorphs along with an egg laying Queen. The Borg attempt to assimilate the ship and it's "inhabitants", not knowing what lies ahead.
The Borg have all of their regular technology.
The Aliens have, well, themselves. Nothing further needed, really.
The Borg can't be implanted by facehuggers, since they are, more or less, cyborg corpses, for lack of a better word. The Aliens have feral attacks and, of course, their molecular acid blood.
The Borg vs. Aliens: who assimilates who?