Point: Benevolent Fungal Collective.  

It has been said that the Assembly was just another group of free floating fungus spores.  Dust has had an enormous impact on the cosmos and microbial life is no exception.  Even as a single host can hold billions Assembly spores, only a few decimal places of a percent of them will become sentient.  Those precious few of their members organizing in the presence of intelligent life.  More specifically, upon and in them, forming the active intelligent and mobile mushroom growths upon their willing hosts.  The services of which are repaid in exchange for massive amounts of endorphin and a vastly expanded life span.  But for their enormously squishy fragility, low population of useful and functional Assembly members would cover the galaxy.  

Traits:  

Pros: Can fully negotiate with every species via direct brain connections (Microscopic Communication), bonus FIDS for bringing alien populations to their planets

Cons: Limited population growth, fragile population, terrible ground forces.