If you didn't know, Dragapult has a ghostly, translucent tail. It's head is shaped like the Diplocaulus which is an extinct amphibian. The tail of Dragapult is like it is because the the tail of the Diplocaulus was never found. Like I said the Diplocaulus is extinct, which also could be a reasoning for the Ghost type. It head also resembles a B-2 Spirit, a stealth bomber aircraft, which is why it shoots Dreepy out of it's 'horns.' A nice play one words there, B-2 'Spirit', spirits can be seen as ghosts.