I don't have much experience on this stage, but there are some notable things that benefit GaW.
Jump-through floor We all know how good GaW is at attacking through the bottom of platforms, so just act as if the stage is one giant platform. The best option the opponent has, most of the time, is simply to evacuate. Some characters can actually challenge you down here, but your 'chute normally is at least safe enough.
Platforms. GaW is good with platforms. There are platforms here. Use them. Nothing too it
Walls Like omega said, try and trap the opponent here. Not a huge boon to GaW, but it doesn't hurt as much as it helps =\
Simply STUPID blastzones. This can hurt or help, depending on how well you know the stage. Your chute is good for pushing people a little further, while being very safe for you to use. This helps everywhere. Some stops, like the one on top of the castle (NOT with the Shine thing) has stupid close blast zones on either side. Your d-smash is gonna be a huge threat. D-throw -> D-smash has never been better, and if the opponent is good at teching, or their character can buffer a roll, then just use that knowledge and techchase. Normally my opponents just DI and tech away from the dumb blastzones if they are in a disadvantaged position.
I don't really know about numbers, a good CP if you aren't confident on RC (If you aren't confident on RC, you should CP... another character) and the other "good" GaW stages are banned.. This stage is very seldom banned.
With this post, I should mention... I am gonna start contributing more to these things =].