Where exactly in route 15 is delta girafarig?
I don’t know, i can only say i find an hidden grotto in route 15, i hope to find here Delta Girafarig
Route 16, there is a house with a lady inside, she gives you delta girafarig in the form of a trade.
He will give you Delta Girafarig only for a pokemon with “elemental hyper beam”, (example Hydro Cannon)