To get to new mauville
in that city, use surf into the water than in the cave at the center, u will need it.
which key if its the secret key u have to get it on the 3rd floor and talk to the man with the girl he'll say enter a code. there are 2.the first is everyone happy and the 2nd is wi-fi connection and he will ask u to go to mystery gift save after getting the offer and go get the key to unlock the basment in the galatic hq and get rotoms formes
To remove key items in Pokémon Emerald using cheats, you can use a GameShark code. One common code is "BFF956FA 2F9EC50D," which allows you to remove key items from your inventory. Activate the cheat, and then access your bag; the key items should be removed. Remember to disable the cheat after use to avoid unintended effects.
it is impossible to do that unless you start the game over again and don't collect the item you don't want
The key is laying on a table in the deepest part of the Pokemon mansion. You can find it lying on the table and it's used for opening the gym.
in that city, use surf into the water than in the cave at the center, u will need it.
Go to the uderground entrance and look for a locked door.
On cinnabar island you need the key from the Pokemon mansion (basment)
The lift is on basment floor 2 but the key is on basement floor 3.
There is no key it opens when you become a Pokemon champion.
select
you go to team rockets in golden rod to the radio stashon and get to the top floor deefeat the imposter and he will give you the basment key k
where you use the key to turn on the quary.
Watson gives it to you
say thank you
As far as I know there is no code for key items.
Ruby & Sapphire Key