The base in Mahogany is completely abandoned. There's nothing in there save for a few Pokémon.

[And possibly some of the Electrodes Kimblee was using as traps, whoops.]

I'm assuming you're attempting to complete the Badge challenge? What do you intend to do in the base?

[That does raise some warning flags; it's possible that Itachi is looking for things to use against the organization. The Mahogany base doesn't have much of anything there, so he sees no harm in answering the question.]