What you need to do:
-Beat the Elite 4 and unlock Kiloud City
-Get your friend code (Available in the friends list from 3DS dashboard)
-Post your in game name (IGN) along with your friend code, and start adding away!
*Note if you skip step one your third slot will be unavailable, so don't be that guy! Also note that even after you beat the elite 4 the person you added and yourself must be online (in game) at the same time otherwise the third slot will still be locked.*

The friend safari will provide you with a wide variety of pokemon to be caught. Each trainer has a predetermined type, and pokemon (3 total) based on their friendcode. If you wish to reset your friendcode you have to do a factory reset. Not recommended however. If you get a shitty safari, hey shit happens. Im sure people will still be kind enough to add you regardless! In addition the the broad selection of pokemon that are available in the friend safari Pokemon with perfect IV's and hidden abilities are also able to caught. However if the third slot of a trainer is still locked, pokemon with hidden abilites will NOT be able to be found. The third slot must be unlocked in order to find pokemon with hidden abilites.

I'm looking for Clefairy, Nuzleaf, Maractus and Cacturne safaris