Go above Mauville and past the desert till you find a different looking tree with a man standing in front of it. Go talk to him and he will give secret power to you.
Chat with our AI personalities
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!
Get the TM secret power teach it to a Pokemon then find either a tree with vines, an indent in the wall or a big bush use secret power on these to create your own secret base.
In the game Pokemon ruby destiny
no where
You can't find Eevee in Pokemon Ruby, but you can trade for it from Fire Red, Leaf Green, and XD.