POKEMON is just a generic name. Should only be used for sizes, not addresses.CURRENT_POKEMON is the current pokemon on a walk. Unknown if "joined" pokemon are treated the same.EXTRA_POKEMON is the pokemon gifted as an event by CMD_C2 or caught on a special route.ROUTE_POKEMON are the three regular route-available pokemon. Stored in route_info_t.route_pokemon[].GIFTED_POKEMON exclusively refers to the pokemon gifted by CMD_C2.SPECIAL_ROUTE_POKEMON is the extra pokemon on the special route. Stored in special_route_info_t.special_pokemon.
ITEM is a generic name, only used to refer to uint16_t le_item.DOWSED_ITEM is an item currently in the inventory that was obtained through normal dowsing.EXTRA_ITEM is an item currently in the inventory that was either obtained though a CMD_C2 gift or dowsed on a special route.ROUTE_ITEM is an item not currently in the inventory, that is available to be dowsed thorough normal dowsing.GIFTED_ITEM exclusively refers to the item gifted by CMD_C2PEER_PLAY_ITEM is an item received after engaging in peer play.SPECIAL_ROUTE_ITEM is an item not currently in the inventory, that is only available to be dowsed though special route dowsing.