fly to the pokemon center and take a left, you will see a house. go in the house and talk to the kid. he will tell you what route your base is on.
in the secret citey mcors citey
from your enemy teams base
All decorations can be found in stores throughout the game, you just have to find the correct store.
its on rought 128 in sappire/team oqua, ruby/team magma, and not shoure what criminals in emerald
You must find a Bagon in a secret room in the meteor falls and train it.
To find your Secret Base, talk to the short guy in a house in western Mosdeep City. He will mention a base on a certain route. Go there, and find your Secret Base on that same route!
in Pokemon diamond and pearl just go on your udventure and you will find it but in Pokemon sapphire,ruby it's hard to get it
Through the magic of the final axe of the Egyptian Pokemon
There is no Pokemon mansion in sapphire.
He is not in Pokemon: Sapphire. You will not be able to find him. He is in Pokemon: Diamond, Pokemon: Pearl, and Pokemon: Platinum. You will definitely have trouble finding him in Pokemon: Sapphire.
Secret bases are hidden around hoenn its a hideout for you, all you have to do is find a big bush or a tree with vines or an indent in the wall and you use the TM secret power on it and a hole will appear or a vine inside is an area where you can use decorations to make your own secret hideout, if you mix records with friends they can battle you in your secret base and you can do the same if they did that.
you can't find it in Pokemon sapphire, but you can find it in Pokemon ruby. Hope this helped. :-)