While going through Pokémon Brilliant Diamond & Shining Pearl, players may find themselves without the useful Technical Machine (TM) and Hidden Move (HM) Defog, which is rather easy to miss. TMs allow a move to be taught to a Pokémon once, and HM variations often contain moves required for traversal like Surf, Cut, or Defog. Strictly speaking, Defog isn't a necessity to beat BDSP, but it makes traveling through foggy areas much less of a pain.
Defog does exactly what the name implies - it dispels fog, but many players may have missed it while going through the game since it's off the main route. Pokémon BDSP's TMs system has one important difference from past games in that the Pokémon that are taught an HM don't need to remain in the player's party of six in order to use it. This helps players keep their team composition intact and makes the inclusion of one Pokémon loaded with HMs an obsolete necessity. There are plenty of HMs to be found all throughout Sinnoh, and they can be taught to Pokémon that are usually kept in storage, letting the player simply use the Pokétch instead.
Defog is so hard to find because it's sequestered in the Great Marsh, Sinnoh's Safari Zone. Players are never actually required during the BDSP main story to go into the Safari Zone, which is located near Pastoria City, but it's a great place to catch Pokémon and find items. The Safari Zone also offers a change of pace to the Pokémon formula, not allowing players to battle the Pokémon inside, making catching them more or less a game of chance.
How To Get Defog In Pokémon Brilliant Diamond & Shining Pearl
Luckily for those looking specifically for Defog, it's rather easy to get. Players just have to travel to Pastoria City, and enter the Safari Zone. The attendant will make players pay 500 Pokémon Dollars to enter, which grants them 30 Safari Balls and 500 steps through the Great Marsh before they're called back to the entrance. Paying the fee and entering is practically all that's required for Defog, though, since a green-haired NPC directly to the right upon entering will give the player Defog when spoken to.
Players can either stick around and get their money's worth out of the Safari Zone ticket after getting Defog or just turn around and leave the Great Marsh if that's all they're interested in. The Safari Zone is a neat idea, but was practically phased out of the games by Sword and Shield's introduction of the Wild Area, and could be reintroduced in future Pokémon games with new mechanics. So many players missing Defog because of its location in Pokémon Brilliant Diamond & Shining Pearl's Safari Zone is a good example of how useless the area can be.