As far as fighting types go, Lucario works wonders, IMO. He gets a wide array of moves, and also fills up that rare niche of "special attacking fighting type" if you want it to. Mine's a Calm Minder (though if you, unlike me, actually have the patience to train up Riolu to that high of a level, you can make him a Nasty Plotter).
I also suggest an electric type of some description, as your team will -probably- have trouble with the flying gym when that ever comes around. I picked up Ampharos, but he's slow as dirt. At least he hits like a truck. *shrug*
It never really occurred to me to raise a diversity of pokemon in preparation for whatever might be thrown at me, but that's actually a very good idea. As for me, I'm going to try and find a Starly so that I actually have an answer to fighting types on my team (my current team is Lucario, Scolipede, Gyarados, Swampert, Ampharos, and Houndoom).