Glad to see you tried out Fox Anther, he really is extremely underrated (I see people speculate him being in low tier or the bottom of mid tier all the time). I might come up to one of Rofa's biweeklies sometime. I'd be interesting in playing your pikachu and seeing how much it differs from Pika Pika's playstyle. Anyway, Fox does fairly well against G&W, one of G&W's main advantages that's often cited is his ability to live to high percents despite his light weight thanks to his dair and excellent recovery. Fox completely eliminates this advantage since he can kill G&W at 80% on most stages with upsmash (the majority of stages in this game have the same ceiling height). As said earlier, you need to work on your lasers more as the ones you used were useless. Also, it's good to try and approach g&w instead of letting him approach you, his bair will win every time. However, you need to be careful when approaching him from above due to his up-air, he seemed to set you up with it a few times, avoid that. You need to constantly pressure G&W with lots of variety to actually stand a chance, which you did a good job of with jabs and shines mixed up in your game. You neglected to use f-air enough, it's very helpful on g&w. Also, downsmash and forward smash aren't that useful against g&w except for racking in damage. Don't use them much (you didn't use them too much, I'm just throwing this out there). They don't set-up for anything good against g&w. However they both are actually useful against Snake and some others. Haha. Also down-b is a great way to avoid punishment from g&w's upair & up-b set-ups, it's actually insanely helpful in all matches, haha. Also, although the situation almost never arose, Illusion Canceling at the edge (not Illusion fake-out, actually using the edge to cancel your illusion, there's a thread on it on this board) is a very easy thing to learn and helpful as an added option to recover and is very safe. If you have any questions about match-ups send me a PM, I have actual tourney experience with Fox unlike others.
Oh yeah, wall of text.