These bosses can give a Gen 7 Starter Egg:
Ghost Kian – Devil’s Den (SouthWest of Mysery Town)
Will – Sewers (NorthWest of Town – beside Manor)
Basher Brian – Dog Bite Bay
Malicia – Cauldron in Malicia’s Cave
Soldier Rufas – Army Base near Area 61
Alien – Deepest Underground at Area 61
Demon – Nether (Can’t return if you die or leave)

These bosses do not give Gen 7 Starter Eggs:
Lucius – evening/Night Only – Dog Bite Bay (Start quest by talking to Roy at NE area of Dog Bite Bay.  Chance of receiving a Lycanroc.)
Holes (Mirror Match @ Trainer Level) – Cursed Cove
Ghost Kian – Spider’s Nest
Meli – Dog Bite Bay
Creepy Clive – Shadow Hill Cemetery (Starts Will Sewers quest)
Jess – Evil Ridge (Northwest of Mysery Town)
Freaky Fisherman Fred – Cursed Cove