85h is an offset in the data structure of 4th Generation Pokémon, and shows how a Pokémon was encountered. Currently 85h has no relevance to gameplay, but in certain cases it can be used to determine the Legality of a Pokémon.
00 - Egg/Pal Park/Event
02 - Tall Grass/Honey Tree
04 - Dialga/Palkia
05 - Cave/Hall of Origin
07 - Caught in the Water
09 - Caught in Buildings
0A - Great Marsh/Safari Zone
0C- Starter Pokemon/Fossils (D/P)
18 - Starter Pokemon/Bebe's Eevee (Platinum)
17- Giratina (Origin)(Platinum)
??- Giratina (Another)(Platinum)
??- Fossils (Platinum)- 18?
??- Honey Tree (Platinum)- Pretty sure its 02 but not confirmed.
??- Dialga/Palkia (Platinum)