I have two questions really, both related to breeding:
Can someone explain how exactly destiny knot works in simple terms, I have looked it up several times and just get more confused every time.
Regarding hidden abilities, can those be passed down from the father onto an egg of a different species? For example if I had a male multiscale dragonite and a female Infiltrator noivern, is it possible to get a telepathy noibat from that combination?
The Destiny Knot can pass down 5 IVs from both parents put together, and these five are chosen randomly. The Destiny Knot will, to my knowledge, not pass down more than five at a time.
The father's ability does not matter when passing down hidden abilities. The mother's ability is the most likely, by far, to be inherited by the offspring. The other abilities that may be be on the child will be one of the main abilities. Hidden abilities cannot be passed down unless the mother has the hidden ability. So in your case, finding a female Noibat with telepathy in the wild is your only way to get a telepathy Noibat.