Fox doesn't do too well against Samus. He does win the match-up, but I don't think by much.
-Mixing up block pressure into grabs, or dding into grabs are useless; throws lead into nothing unless you're near an edge (potential edgeguard)
-Even still, you can't edge-guard her sometimes because of the invincibility on the upB
-You can't attack Samus' shield AT ALL because simply hitting it puts you at a disadvantage and gives Samus free damage. UpB has 3 more frames of invincibility than shine does.
-She CCs nairs/bairs for a long, long time, and when you try to dair->shine..it whiffs sometimes because her stun animation from the dair moves her body back a bit.
-You have to resort to lasers only, and dair->shine -> usmash. This is assuming the dair to shine even combos because of the strange effect dair has on her. Again, if they see you coming and shield, you can't shield pressure like you can on most other characters because upB is stupid. She limits you to the point where only 3 things consistently work on her. (shine->usmash, laser, spaced bair) She doesn't have to change the way she plays at all until you start laser camping her.
i have some more earlier in this thread but i'd like to write a bit more about the samus matchup after playing hugs for like 15 hours this weekend.
general
overall, this is not one of fox's best matchups, i think it's even or very slightly in fox's favor. the advantage you all have is she's one of the least represented characters and there are very few players who really use her at a top level.
shield pressure and her up+b
it's possible to attack samus' shield but you have to be very very precise and clever. if you rush in like a noob you will eat an up+b every single time and possibly a dsmash if they land on a platform with you. your method of shield pressure should consist of hitting her with a well spaced nair or bair that hits LOW on their shield, and shining after. every samus has their comfort zone with up+b, so take note of how proficient they are with it, and shield pressure accordingly
if you did it correctly it's possible to bait out a whiffed up+b which can sometimes lead to a very damaging uair chain (it's commonplace to get 2-3 uairs at low-mid percent on samus.) be very aware though, shield pressure is NOT guaranteed, even if you do it nearly perfect, a good samus will be able to up+b you out of almost any unspaced attack.
baiting out up+b is a very important part of this matchup. you can do this by doing low aerials and shielding after, by nairing their shield and dashing away quickly, and by run-up shields.
edge guarding
edgeguarding IS viable, but i think most foxes don't know exactly what to do, because it's very difficult to pull off. basically, your first objective is to eliminate their grapple. one of the best ways to do this is to non-fastfalled weak bair off the stage and hit them right as they begin their grapple. if you get them, don't be fancy and try to shine after, just recover and get back to the edge ASAP. another way to get rid of their grapple is to refresh your ledge invincibility and attempt to shine them as they pull up to the edge. this is a bit harder and it depends on where they grapple'd the stage, so i prefer bairs.
once their grapple is out, they're forced to up+b. do NOT attempt to dsmash edge guard them. any samus worth their salt will sweetspot it, you will probably get hit by the end of the spin attack and get forced on the ground, or you will get fair'd -> dsmashed during your lag. low angled f-tilt is not a bad idea and is totally safe from punishment, but won't get you a kill.
what you want to do is combine the invincibility you get from grabbing the ledge with the bit of invincibility you get from standing up from the edge, and usmash (you can walk forward and dsmash if they're not at kill percent) them when they touch the ground. i guess it's similar to edgeguarding sheik, but it's very tough and you need a lot of experience with it or else you'll get hit with spin attack and get forced on your back.
lasers
lasers are very good in this matchup, samus is very slow in the air and you can get easy free damage when she's recovering or coming down from an uair. even though samus is tall, i still suggest sticking to single lasers over double lasers. single lasers let you be more mobile and make it harder for her to catch you. i suggest dash dancing and using a single laser to bait out her wavedash ftilt, and fulljumping over her with bair to punish.
grabs
grabs aren't THAT bad. you won't combo from them at all, but they're a good mixup because samus relies on her up+b out of shield so much, it's pretty easy to catch her in shield with grabs and get like 6-14 damage. uthrow is decent because sometimes you can read their double jump and get a back air in, but don't rely on it too hard because it's easy to get nair'd. dthrow is decent, but her tech roll is super long and quick so it's very hard to tech chase usmash. if you can be creative with it and score extra hits be my guest, but it's a risk. fthrow is probably your best bet. it forces samus slightly in the air, so sometimes they come down right after with a nair, which you can grab or usmash oos.
general
your overall strategy consists of reading her WD's back, shielding ftilts, using lasers to manipulate her movement, and not getting *****. also, if you can get samus on a platform, use everything you can to keep her in her shield, she's completely useless on platforms and you can get very easy bairs if you make her make a dumb move up there.
stages
best stage: pokemon stadium
good stages: battlefield, yoshi's story
ok stage: fountain, fd
bad stage: dreamland
