|1||Route 227 — On the ground to the right of a small pond located in the upper-middle part of the route.||No|
The game’s only Charcoal is found on Route 227. It’s sitting next to a small pond at the base of Stark Mountain. But to reach it you’ll need Pokémon that can use Rock Climb and Surf.
As for the item’s effects:
Charcoal is a Hold Item that boosts the power of Fire-type moves by 20%.
Charcoal Location (Step-by-Step)
There is only one Charcoal in Pokémon Platinum, and it’s located at the northern edge of Route 227 beside a small pond at the base of Stark Mountain.
Once you have Pokémon with both moves in your party, Fly to the Survival Area to get started.
Then head east from the Pokémon Center here.
When you reach the eastern mountains, move southeast to get in front of them.
Use Rock Climb on the first rocky wall you encounter.
After Rock Climbing onto the terrace, climb down the rocky wall to the right of it.
Move to the other side of the new terrace (moving right), where there are two more rocky walls.
Scale the rocky wall to the north.
Head up the staircase and climb down the next rocky wall you come to (the rocky wall on the left-hand side).
At the bottom you’ll want to turn eastward and move through the grassy strip.
Use Surf at the ocean and start heading northeast.
When you reach the island with the white house on it, step ashore.
Then cut across the island to the right and use Surf on the ocean path to keep moving east.
Eventually you’ll hit a dead end with some land above you – disembark and head north.
Head northeast past the sign to enter Route 227.
Go all the way up to the northern wall, then ride your Bicycle in fourth gear to jump the ramp and clear the boulder.
Drop down on the nearest ledge (ignore the second ledge to the south of it), and then head westward.
Turn to head north at the end of the path and approach the white house above.
Then take a right turn to go by the house and head up the long staircase to the east.
Turn right at the top of the stairs.
Then you’ll need to ride your Bicycle over the fallen log.
On the other side of the log, make a left turn into the next grassy area.
Turn south and drop down the ledge.
Then climb down the rocky wall.
At the bottom, travel eastward across the terrain, circling around the ponds.
At the eastern edge of this area (to the very right of the lake) is a Poké Ball item.
Pick up the item to get your Charcoal.
Note: This is the only Charcoal you can get in Pokémon Platinum.
Charcoal Details and Uses
The Charcoal is a Hold Item that boosts the power of Fire-type moves by 20%.
Like most type-boosting items, the Charcoal is underpowered compared to items that work more generally, like the Life Orb and the Choice Band/Choice Specs.
There are ways of mitigating the drawbacks you get from the Life Orb or Choice items – but if you don’t want to deal with the hassle and just need a simple item to further boost a Fire-type Pokémon’s STAB damage, the Charcoal will suit your purposes fine.