You can get the BlackGlasses by speaking to an NPC standing inside the Celestic Town shop in the daytime (10:00 AM to 7:59 PM). This same NPC will give you other items during other times of the day, so you’ll only get the BlackGlasses by speaking to him during this exact timeframe.
And this is also the only way to obtain a pair of BlackGlasses in Pokémon Platinum.
Inside the Celestic Town shop is a man who will give you a pair of BlackGlasses if you speak to him during the Day.
This item is one of three types of Glasses items that you can obtain by talking to this NPC at different times, with the other items being the Choice Specs (Morning) and the Wise Glasses (Night).
For the NPC to give you the BlackGlasses, the in-game time has to be between 10:00AM and 7:59PM when you speak to him.
If it is, then just visit the Celestic Town shop and find the NPC inside with brown hair wearing dark glasses himself (ironically).
To get started, first Fly to Celestic Town and head north up the path directly right of the Pokémon Center.
Go up as far as you can until you see some houses, then turn and head west to pass by the old man NPC.
Keep going west until you hit the western edge of town, and the shop will be directly in the northwestern corner here (it has a blue door and it’s next to a small pond of water).
Head inside and speak to the NPC with the dark glasses on.
If your in-game clock is reading a time between 10:00AM and 7:59PM, this NPC will hand you the BlackGlasses at no cost.
BlackGlasses Details and Uses
The BlackGlasses are a Held Item that boost the power of Dark-type moves by 20%. This is also the same primary effect as the Dread Plate.
But this effect is especially useful for Dark-type Pokémon in your party that can take advantage of the bonus STAB damage.
Like most Type-boosting held items, the BlackGlasses offer only a modest power increase – but they come without any of the drawbacks of more powerful items like the Life Orb or Choice items.
- The Life Orb provides a 30% boost to every move the holder uses, but siphons 10% of the holder’s HP with every damaging attack.
- The Choice Band/Choice Specs both offer a 50% increase to the holder’s Attack and Special Attack, respectively. But they force the holder to use only one kind of move until they’re switched out of battle.
So ultimately the BlackGlasses are not the most thrilling or popular item in the game.
But a 20% boost to a STAB-enhanced Sucker Punch is never a bad thing.