And I as I have said before my stratigy is.........i am to tired to type it I hit first and ohko or at least 2ko
You must know by now that to hit hard and hit fast you need high speed and high attack.
So, train him in speed and attack since his attack is better than special. Though Feraligatr's speed isn't that great to start with...
I would train it's special attack and speed. This way, it can have a strong Ice Beam and Hydro Pump instead of only Physical moves. Plus, it will be fast enough to use those moves.