I want to find Venonat but there is no XY location data for it in the database.
Venonat is uncatchable in Generation VI. In Friend Safaris, Venomoth can be found in Poison's Slot 2 and Bug's Slot 3 at a 25% chance each. You can then breed it to get a Venonat, though it may be easier to find a Venomoth from one of ORAS' Mirage Islands.
Venomoth (Bulbapedia)