You don't have to remain passive against a G&W player, Admiral. In certain cases, you could be. But, you never have to play from afar and close the distance when G&W has made an error.
What I found useful is to use the arrows a lot, and heres how. Say G&W is a far distance away from you. You have a ton of different methods at your disposal to attack, but you want to play it on the safe side. You could charge your arrows and dash dance while holding down B. Outcomes are you get a clean shot and can close some distance, you mindgame G&W into pulling out the bucket and shoot in the opposite direction to turning around to shoot again as he withdrawls the bucket, or just shoot up in the air and take advantage of the buckets recovery time and punish like all hell.
Considering his size, he's the perfect candidate to get destroyed with AR. If he decides to cook up some sausages with his B, SH AR into him and slide right in to rack up damage. This will make G&W DI away from you and you can arrow him in the face and proceed to attack with whatever.
If you want to play on the safe side and have good timing with Pit's shield, since a lot of G&W's smashes have some wind-up lag, Angelic Step to shield and grab. I could only see this working with his Fsmash and Usmash, but it could work non the less.
Last, for G&W's aerials, its all about distance. Just play it on the safe side and keep pushing him away, until you have him under control on the ground.
Well... those are my two cents, as I cannot think of anything else. Hope some of this helps,