you use the radar in your pokech' and go to the front of the hotel near valor lakefront
complete the sinnoh pokedex and she will say shes found the key and inside you will see 5 rare candy
If you are talking about the key that allows you to get into the hotel in Canalave city, You must get it from a mystery event . A mystery event is an event held at game stores, such as Game Stop, where you can download rare Pokemon and items to your Pokemon games, such as Diamond, Pearl, Platinum, Heart Gold and Soul Silver. If you go to a mystery event and are able to get the hotel key, you open the hotel and sleep there for the night. when you wake up, you will be in Canalave city in a different time period and will be able to catch Darkrai.
You can only get the secret key in Pokemon Platinum
ok the key should be just outside of hotel grand lake (the hotel the girls at) in the back where the lady who heals your Pokemon not in the hotel itself but outside in the back you will need the scanner to find the key but its on the pavment :D
use the itemfinder app behind the hotel entrance
you use the radar in your pokech' and go to the front of the hotel near valor lakefront
use the item finder thing near the hotel it should be there.
Pokemon event
In Pokemon Platinum you dont get the key from a grunt you get from the detective, before getting the key you have to go talk to prof. rowan in the library .
Check behind the nightstand.
go on Pokemon Platinum Walkthrough you'll might get the idea.
If you have found the Suite Key first, take it to the blonde girl in Route 213, who is looking for her keys to the hotel. She'll reward you a Lava Cookie. (White Flute in Pokemon Platinum)
you have to go in front of the actual hotel building a couple steps in front of it with the item finder app and dont stand on top of it and press a.
complete the sinnoh pokedex and she will say shes found the key and inside you will see 5 rare candy
If you are talking about the key that allows you to get into the hotel in Canalave city, You must get it from a mystery event . A mystery event is an event held at game stores, such as Game Stop, where you can download rare Pokemon and items to your Pokemon games, such as Diamond, Pearl, Platinum, Heart Gold and Soul Silver. If you go to a mystery event and are able to get the hotel key, you open the hotel and sleep there for the night. when you wake up, you will be in Canalave city in a different time period and will be able to catch Darkrai.
You can only get the secret key in Pokemon Platinum