Can an Aetherborn Marauder take +1/+1 counters off a creature that didn't have them (but has P/T to spare)?
From the rules : 


  121.5. If an effect says to “move” a counter, it means to take that counter from the object it’s currently on and put it onto a second
  object. If the first and second objects are the same object, nothing
  happens. If the first object has no counters, nothing happens; the
  second object doesn’t get a counter put on it. If the second object
  (or any possible second objects) is no longer in the correct zone when
  the effect would move the counter, nothing happens; a counter isn’t
  removed from the first object.


Your Aetherborn Marauder doesn't get any counter if the target of its ETB ability doesn't have counters when the ability resolve.