Just going to clarify that the 0x85 encounter hex being "Egg/Pal Park/Event" always in gen 5 is due to the value not being used.
0x85 == Egg/Pal Park/Event = 00, which is zero (can also mean unused).
If it has Black / White as its Hometown, it is unused, not zero (they are the same thing essentially). I haven't seen anything that proves otherwise.
Codr, if thou be lurking, make it that if B/W is the hometown, the Encounter dropdown is set to the Egg/PP/E and is unchangeable (grayed out). <3