He counters Pit pretty well... His projectiles protect from trajectory attacks. His bucket eats arrow fast and it's hard to shoot around. His aerials out-range, out-prioritize, and are just as fast as Pit's. And a smart G&W you easily out-range and out maneuver you. It's almost as though in order to make G&W better, they added a higher tiered character that he completely counters.
Anyway I'm not too sure what to say. You just have to have a better metagame then your opponent. My typical answer of "Powershield then counter attack" is nearly useless seeing as his animations are so short and choppy. If you can pick up on them utilize the Shield Dash strategy. If not I suggest spamming the Powershield when in combat range. Everytime he nails it you get a free hit. Also SlideStepping might come in handy when duking it out at close range, which is certain to happen.
Sigh, I doubt that's much help. G'luck man, tell us if you figure anything out.