During battle, Pokémon can become trapped with various kinds of afflictions, damaging them or hindering their ability to attack. There are many options for curing these conditions, but one of the best is Lava Cookie.
Lava Cookies heal Pokémon in all non-volatile states, but these items aren’t something you’ll encounter often during your travels. But one could be on Route 213.
When you reach the Valor Lakefront, towards the back of town, you can find a blonde woman standing outside a hotel. If you talk to her, she will ask you to help find the Key Suite. This item can be difficult to find as there is no visual indication for its location.
Suite The main location in Pokémon Brilliant Diamond, Shining Pearl
After talking to womab, head south to the entrance of Valor Lakefront on 213th Street. As you walk through the reception building onto 213th Street, if you press “A” on the first block of the wall on the left, , you will recover the Suite Key .
Now just give the key back to the lady waiting to enter her room, and after handing it over you should be able to enter. Enter the room and talk to her, and she will give you a Lava Cookie for your help.
With this item, you can now join the battle knowing that you have another option for curing the conditions your Pokémon may have for the duration of the battle.
https://dotesports.com/pokemon/news/where-to-find-suite-key-in-pokemon-brilliant-diamond-and-shining-pearl Where to find the Suite Key in Pokémon Brilliant Diamond and Shining Pearl