I've found the most success in laser camping, punishing bad approaches with CC shine or upsmash, up air to cover tech in place and solid grab and edge guarding games. If you end up on FD against fox, you need to chain grab to get a real percent going. It works until 65 when no DI can get them out, I like to uptilt them instead of making the last grab, then you got them at about 65ish and can usually bair offstage and cover ledge. I'm just a scrub fox but Nemiak temp is completely right in everything he's saying here. Run shine is especially helpful in this match for both getting a grab, starting thunders combo, or just forcing the opponent to pick an option. Make sure you're not just throwing nairs out in this matchup because if the opponent catches you, they're usually fast enough to punish with something like upsmash or if they're at low percents crouch cancel shine. Remember things like shine OOS in this matchup too if he starts going for your shield. 5 frames is REALLY quick. Dash dance is also super helpful in this matchup as punishing bad movement/bad moves with upsmash, waveshine, grab, nair, and dash attack is helpful (careful not to get CCed if you do the last 2). For me, dash attack is super helpful if they're not at a low percent because you can dash out, then immediately dash attack in. Dash attacks can usually lead into things like uptilt or upsmash. A good nair can lead into dash attack and upsmash too. Remember, just as important as the neutral is, covering options is important too. I've seen players like Zero and Leffen backthrow slightly out of middle of stage to throw the player off for shine spikes, edgeguarding. Good players will DI that so be prepared to cover the platform with usually a nair, and if that doesn't hit, dash attack back. You can see this used in like few minutes in Leffen vs. PPMD at MLG. Remember other basic things like to ledge dash with invincibility, upsmash oos, downsmash at the ledge, downtilt and dash attacks to cover missed techs/poor spacing. most importantly though, i think you should use up air on tech in place. According to the Ace Arwing Pilot Fox Mccloud guide, the first hit activates on frame 8 and the second hit ends on frame 14, so it's both fast and ends quick. The lcancel is only 9 frames, so you can instinctively cover tech in place and then move on for roll away or missed tech. Lucky mentions up air on tech in place in his Favorite fox techniques guide. Upair (on super low percents) can lead into shine (but you shouldn't try to go for anything from that since they will act quickly after being hit from the air), upair again, upsmash, and probably a number of other things. AMAZING coverage since you can scare the opponent into not teching in place. Your OOS options are almost always going to be wavedash out, jump out, bair, or shine. That's probably all I got for now at least. In study hall at school. I know this is months later, but good luck man. Check out those guides.
Edit: oh crap this is pm not melee