First talk to the grunt outside of the galactic building and after that looker will talk to you.
After that go to the house where you found HM Fly and walk to the door. looker will unlock it and then just fight the grunts until you find the key.
It depends what your talking about. . . The key in one of the 3 lakes? well if you mean that one. . . go to valor lakefront outside of the hotel where the lady is, walk three or four steps front, touch left lightly don't move just look left, and then press a or whatever and you will find a key that will open the other hotel. :)
First, you must find a Razor Fang (item). Then give it to your Gligar. Then level it up between the hours of 4am and 8pm.
first you beat the gym leader then fight the Galactic goons and get the Pokedex back the talk to Looker then goto the ware house when you get to the teleporters keep going intill you find a room with three boxes and a Galactic goon and theres 1 poke ball and that's the Galactic key
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 .
go on Pokemon Platinum Walkthrough you'll might get the idea.
To get the secret key, you can go to nintedo wifi and mystery gift there
It changes Rotom's forms, but it only is in Platinum.
first you beat the gym leader then fight the Galactic goons and get the Pokedex back the talk to Looker then goto the ware house when you get to the teleporters keep going intill you find a room with three boxes and a Galactic goon and theres 1 poke ball and that's the Galactic key
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 .
go on Pokemon Platinum Walkthrough you'll might get the idea.
You can only get the secret key in Pokemon Platinum
you need wifi do get it!
its easy but hard
check serebii.net for info on upcoming events for Pokemon Diamond,Pearl,Platinum.
It's exclusive to Pokemon platinum version.
platinum is coming to America in 2009 ask someone in japan
Looker will meet you at the warehouse and he will have the key.
Go to www.pokemonplatinum.com and click mystery key