General
Fox is fast, strong and good at avoiding damage.Some notes with Fox:
(Up+B) - Fox's recovery can be aimed. After initiating the 'charge', push the direction you want him to fly. This allows explosive moves towards where the action is.
(Down+B) - Fox's shield can deflect most projectiles, making him the natural enemy of Samus and Link, as well as any thrown object. Most of these objects are returned towards the thrower able to do quite a bit of damage to them.
Throw - Fox is an excellent thrower, he has a quick grab and long range throw. This can easily become the basis of your strategy with him, hug the edges and grab recoverers to quickly hurl them off again.
Aerial Attacks - Fox flies a Starfighter, naturally he's at home in the air. A pretty effective jumper with an array of powerful air executed attacks and kicks. When not throwing, Fox should be in the air, keeping him air borne keeps him where he's strongest.
Juggle - Fox can quickly execute (Up+A) attacks while in the air to knock other aeriel enemies upward, then land and quickly launch the same attack. Using this method, one can keep an enemy in the air, doing consistent damage to her until her percentage is high enough to launch them laterally. Alternatively, the juggle is strong enough to throw them so high they get a KO.
Speed - Fox is one of the fastest characters to play; using this in combination with his Aerial attacks is very effective to keep your enemy guessing and off guard. Fox is able to make quick hits in and then make getaways just as quickly when heavier fighters retort, allowing him to get into the air to make another aerial attack. In addition, his speed is half of what makes him such an effective thrower.