Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Welcome to Smogon! We have a simple questions/simple answers thread pinned to the top of the Orange Islands thread list (Edit*: the title is Have a question? Ask it here!) dedicated to answering little questions like this, so please use that rather than a dedicated thread.
That being said, here's Serebii's list of Friend Safari Pokemon and their abilities. You'll have to decide "usefullness" on your own though. http://www.serebii.net/xy/friendsafari.shtml