Ok, this match is no worse than even. I consider Fox to be a MK counter in this game, except nobody expects it. Of course the match is still hard, and takes some getting used to, but it's certainly not bad at all.
First of all, if Fox is above MK and smart about it, Fox can't be cleanly hit. dair always trades or beats MK's moves, with the exception of utilt and nair sometimes. It beats uair. It beats upB (the most popular MK strat). they can shield it, but if you are fast about it, your utilt or jab WILL beat their dsmash coming out. If a Fox lands behind MK with it (which he always should), the MK can't even grab out of it. MK can't land a legit grab combo on Fox, really, but his grabs set you up to get hit again, if the MK is smart
Bair beats the range of all of MK's aerials, so the fox player should be able to completely control the air game here...which is an oddity against MK. This means MK has to play a mainly ground game, including certain SHs, grabs, shield smashes, mainly...and upB sometimes.
SHs can be beaten, as I said, with either FH dair or SH bair. If the MK is shielding, try to land a dair behind his shield...a grab can be spot dodge dsmashed...either that or wait out the spot dodge to usmash or something. UpB is beaten straight up from above with dair. If you are in front, be ready for the glide attack. If the MK player attacks the shield with the tip of his sword, you can beat it, roll away. You CAN beat a glide attack higher on your shield or closer to you with grab or usmash out of shield...yes, they both beat the dsmash if you're fast enough.
Tornado is completely taken out of the game here...You can attack it from above with Dair, with good spacing... If you are on the ground, you can shield it, and sometimes punish it afterward with a grab (best choice) or usmash. if you get hit by it, YOU CAN DI UP out of it...very quickly, and come down with a dair on him in his after lag...it works REALLY well...
Also, at very good %s, your smashes will combo out of dair...usmash out of dair (if fast enough) combos around 80%, which kills MK instantly. a Fox usmash kills MK starting around 65% before the hit...so watch for that.
now for some general strategy in the match:
Nair, Bair, and Dair are your main aerial choices here...imo, Fair is harder to land and lasts long enough so he can punish you for it, if it doesn't work. Nair is overall solid for an aerial game. Bair beats his aerials with proper spacing. and dair goes through everything from above...and combos into everything
be SURE to land Dairs behind MK's shield...every time...this is important. If MK is trying to utilt you out of dair, shine stall it until you can land it...that's a freebie hit.
Lasers are not useful for camping here...HOWEVER, using them to recharge your smashes is money...I love it.
If MK is comboing you up with uairs, start mashing dair, and it will win...
Basic things of being unpredictable apply. Yes, MK can punish you if he guesses you out.
WATCH for edgeguarding... MK can edgeguard you pretty well. Illusion is your best friend here...Usually, MK will commit to come after you, so an illusion back to stage is usually safe. DO NOT recover low, if you can help it.
Dont try to edge guard MK, except maybe trying for a gimp edgehog on a lazy MK. Sometimes, you can land a dair on him off the stage, but it's really never worth it. If He's on the ledge, you can punish him for a getup attack, ledge jump, or ledge hop with dair dsmash...which can kill pretty early near the edge of the stage. Howver, if he sees this coming, he can wait and hit you, so basically, be smart about it.
M2K and I played this match at FAST1, and he was amazed by how many times I could go through his stuff...and how dair comboed into everything.
Overall, the match is VERY winnable...especially against MKs who don't know Fox is so good...
I give it a 6-4 in Fox's favor.
EDIT almost forgot CP stages
FD is really good for you, as it's wide and he can't hide under platforms.
Smashville is also fairly good.
actually, a lot of the stage are pretty even for you....