I'm gonna clean this up before it's put into the OP, add some stuff on the shield game (since Sheik's shield is a strong option vs Fox but there's a lot to it) add stuff on gimping (I feel silly writing about gimping because I'm so bad at it but whatever the guide's not complete without it I guess) but here's a really rough version of the Fox section atm. Some stuff repeats. This hasn't been seriously edited yet so read at your own risk.
Sheik vs Fox
Hard MU. For either character. Requires a lot of self-control because he's basically always trying to bait you or out maneuver you. Even when he's in your face doing shield pressure he's trying to provoke something so he can **** you for it. This makes a lot of typical go-to defenses, jukes, and such a bit nerfed. In exchange, Fox is squishy as hell and Sheik has answers to just about everything he does.
One of many challenges Sheik faces in this one is how strict Fox can be about timings, positioning, and spacing. The fact that Sheik is airborne for a while works for her at far spacings because it grants a large window to reactively fair (or whatever) against approaches meant to go around things (dash FH stuff and anything off platforms, basically). At closer spacings, its height can be a liability (though it can work). This is where the MU is tricky. Ground stuff is generally strong vs close Fox but the fact that her ground moves are so vulnerable to crouch (or they're grab) means further emphasis is placed on creating reaction windows with movement (WD back) so you don't misstep into a dash shield, crouch, or similar. Furthermore, Fox can simply out-time your attack even vs your efforts to out-time him if he just makes a better play. Fox and Sheik, woefully, both have answers for each other.
On that note, if the Fox has weak timings, just flail and cover your retreat aerial with whatever. But good Foxes can get you for this. People bad vs Sheik usually lose to decently executed move spam, crouch grab, jab reset, Nair OOS, or b-throw. So if you suspect badness on your opponent's part, run a diagnostic for any of those (especially if you have a big lead). Sheik is somewhat squishy (she's not so much frail as she is susceptible to certain things really badly) but learning your opponents limitations is worth X% in combo damage. Sheik has a godlike disrespect game vs people that don't understand the nuances of fighting her.
Anyway, moving along to stuff that works or is true because they are factual & good. Awesomely, Fox's attack game is somewhat constricted vs Sheik for similar reasons it gets funneled vs Peach. Sheik is as heavy as Peach and carries a bunch of frame 5 crouch options (tilts and d-smash). She also has as good a crouch grab as you will get without picking Marth. She has a faster Nair OOS and WD. This means Fox has to put some effort into pressuring your shield. Moreover his shine grab isn't super scary to Sheik either - if his shine is staled once then you can Nair on it legitimately. As a frame 3 jumper, Sheik has a good OOS against shenanigans and such (Sheik is generally good vs shine-based pressure but runs into trouble when people try to fish for her OOS jump stuff [or shield grabs] 'cuz, again, duration of a Sheik jump is long). Sheik's defense comes with other limitations too - ever notice how people don't generally avoid approaching Sheik the way they do Peach? This is because Sheik's attacks generally have percents where they go "online" whereas Peach's stuff generally works at any percent. They also require hit confirms & some vague amount of reaction to follow up on whereas Peach's hits hit hard immediately. Why is this important? Psychology time! The focus when being attacked & defending is more to break the attacker's stance - not so much comboing (people drop combos when they're trying to regain footing or are staggered way more than when their stance is proper). Being able to combo perfectly when staggered is a power only Armada and 2K7 M2K really seem to have - it's very rare to be able to punish perfectly, regardless of pressure & where your focus is.
This means that, though Sheik can crouch into counterattacks effectively, her counterattacks (minus grab, kind of) have limitations. Foxes that understand this can be pretty bold about what they do sub-30% so long as it handles grab and grab setups decently (which can have varying levels of difficulty, depending on the Sheik's handler). Anyway, point is there's a rough 30 percent or so on Fox's fresh stock and Sheik gets better as Fox eats damage - Fox improves a bit but mostly stays about the same regardless of Sheik's damage (he picks up some auto-death combos at some point and at like certain percents he can be more bold with sex kicks vs grounded Sheik). The first 30% can be really rough without a good grab because trading is really strong for Fox (14% average move vs 10% average move) and he's better at getting his low percent BnB combos (does Sheik even have really sophisticated low percent BnBs on Fox? Most of her stuff is freestyle or reaction d-throw regrab IMO) started because of dair, shine, generally higher BKB moves, and u-throw.
Because Fox will want to avoid your naked grab as much as possible (especially at low percent) we need to know what he's going to do and how to counter it. This can mean setting up a grab or just taking the stray hits the anti-grab strat leaves him open to. The ball's really in his court on this one - trying to force it into Sheik's is going to go badly.
Fox's anti-grab movement...
A simple grab avoidance strat is to play platforms and to play mostly bait-oriented. Fox is probably the best at this style of play. That said, Sheik has answers. Aerials, especially bair, are strong vs Fox because their range & priority enables them to out-space Fox's legs. You're rarely going to be actually chasing Fox up to the platforms with this or try to intercept his movement path directly - that's very dangerous because even slight timing or positioning changes by Fox can ruin the strategy. Instead you're usually going to counter-bait and try to make him fall on top of it. Going for uairs to start combos can be worthwhile but the narrow hitbox and vulnerability to slight position changes makes it dangerous (although not going for them period can also be a mistake because they're her best combo starter vs platform camp after 20%).
Against more conventional Fox play (with the ground, dashing, jumping, etc), fair and bair are still very good at low percent. Done properly, both can be used vs CC with reasonable success. With a proper reaction & the right spacing / timing mix, SH back fair can interchangeably beat SH and FJ aerials by Fox. Bair is obviously strong vs Foxes that play above Sheik and is useful for the range (low bair > dash away is very hard to punish directly). That said, they also require a jump commitment - this means that they can be stuffed if the spacing is even slightly off and then you're in the air with Sheik being comboed by Fox, which is where Sheik is most vulnerable - Fox's ability to launch her in tons of combo situations coupled with her defensive mix (low priority below, light-medium weight, semi-FFer) often makes her combo food. That said, spaced fair & bair are solid low % damage tools. They sometimes can illegitimately lead to grab too (fair > grab is a classic). There are also some legitimate grab setups off them on airborne foes too, which is dandy.
At low percent you can do a good amount of stuff with needles. Hitting him with a full set if he commits far away helps get him to the magic 24% (use if he's camping or trying to do a juke or bait from the top platform to the floor on a larger level like Battlefield or Dreamland). Descending air needles can combo into grab (obviously useful). Finally, lingering needles can be used to control space in an odd way. You can put needles on the ground and stay behind it (usually you shield or WD back if they come in at that point). If Fox's attack touches the needle, he hits it and goes through hitlag. This extra lag usually nets a free hit (likely grab) and makes his aerials shield grabbable (which is ****). It's a good tactic for keeping breathing room or funneling approach options to certain spots (or even getting grabs on inattentive opponents).
You're going to want be really good at reacting to approach cues. A common misconception is that Sheik works in neutral on prediction. She can, I suppose. But she benefits tremendously from you constructing parts of her defense more reactively - attacking their attacks when they commit (or can't deal with the attack well) and otherwise maintaining a strong posture & defense. Being able to recognize Fox's commitments during FJ stuff makes it way easier to counter - if you can't, you're liable to be ***** by his "vertical dash dance" (his variable DJ game is really strong - one of his best tools vs Sheik and many other characters).
Tilts deserve a note for low percent play because u-tilt and f-tilt have some situational uses even before they produce knockdowns. U-tilt, because of it's ludicrous IASA frames following the 2nd hit, is a reasonable option vs Foxes that play directly above. It's one of the more legitimate ways to combo him into grab at this percent. However, it often trades with his more priority aerials (bair, nair) which can be dangerous. That said, it can beat either with better positioning / timing and the super low KB on both hits gives it odd interactions with SDI, fast-falling, platforms, and shines. So it's far from 100% reliable even if it can lead to incredibly convenient plays (leading into grab can often solve the low% problem or even kill Fox outright). Finally, f-tilt is an okay choice if Fox SHs a lot because barring an SDI you can often f-tilt, stun him long enough to be forced to land (giving him 4 frames of inaction as he lands, plus whatever f-tilt did). By forcing Fox to do this, you create a window to grab his landing (which can be really powerful). That said, at the sub24% range, f-tilt (overall) isn't nearly as powerful as it gets as the stock unfolds and fair > f-tilting blindly will get you killed by counterattacks at low percents. Follow fair baits & protections with movement at low percent (most of the time).
D-smash sucks until 18-20% or so. Period. Unless you can hit multiple hits of it (near the edge, backwards d-smash, other janky things, etc). When it forces knockdown it's main uses are crouch option, combo finisher, and combo linker on staggered foes. It's also good at punishing misbehaviors with the tech window - you can often follow up on non-teched d-smashes with dash attack, grabs, or even more d-smash (shoutouts to Drephen).
General defense stuff:
You're going to want be really good at reacting to approach cues. A common misconception is that Sheik works in neutral on prediction. She can. But she benefits tremendously from you constructing her defense more reactively - attacking their attacks when they commit (or can't deal with the attack well) and otherwise maintaining a strong posture & defense. Being able to recognize Fox's commitments during FJ stuff makes it way easier to counter - if you can't, you're liable to be ***** by his "vertical dash dance" (his variable DJ game is really strong - one of his best tools vs Sheik and many other characters).
Dash attack gets its own section.
A lot of people, I feel, struggle with dash attack placement. Partially because they misunderstand it. To clarify, dash attack has a small series of hitboxes above it - not in front. Dash attack is solid for sneaking below moves but bad for challenging them head on (it can lose to virtually anything if it doesn't out-time them). This makes it's only merit an approach based on its high horizontal attack space stuffing moves. It's not awful, but it's undeniably flimsy (especially when compared to the rest of her). If you really must dash attack approach Foxes, it can work... but understand even her grab (and nair) covers her front better than dash attack and Sheik-savvy Foxes basically always accommodate that lunge into their defensive spacing - so you need to catch them off-guard, which is hard.
Moving on - aside from awkward, spontaneous approaches, dash attack is primarily used for combos and to lag-punish with its crazy lunge & attack speed. It can be used to cross up shields and bait OOS actions that barely whiff (excellent vs low range chars). Strong option at 20%+. Its main shortcoming is its weakness to ground tech on grounded foes so mix it up with grabs and tech timing punishes (when possible) to discourage such behavior.
Brief talk of combos...
In general, your combos on Fox are going to set up their finishers by a mix of throw, tilts, dash attack, her launch aerials. U-smash also comes up at low percents. Dair is a very strong option whenever possible because of the lower KB than uair, and the speed at which Sheik can action to follow it. Reverse hit dash attack is also important trick to know because it counters the old adage - "Just hold away from Sheik." It also opens up opportunities for very optimal combo extensions (dair & uairs).
Now, after all that prep, we need to finish. This is the easy part because she has an insanely solid, single move finisher that denies Fox precious recovery height. I obviously refer to her fair - this is what you pick fof consistency because it's easy to hit and has a consistently reliable trajectory. Flashier kill options include eeak aerial > strong aerial /d-smash. These kinds of finishers are also solid and prey on the habit to survival DI for fair (think Falcon DI traps except Sheik's less good at horizontal air combos). Finally, we have my favorite - tipped u-smash. Tipped u-smash is generslly considered a flashy, overkil choice but it has strong strategic merit beneath how awesome it is. It's essentially a attempt to plan around & counter survival efforts of people who attempt to stay mid-stage when Sheik combos them and build height. Tipped u-smash combos are usually a mesh of dash attack, dair, u-tilt, f-tilt, and on occasion uair.
Now to talk about Fox's combos...
Escaping Fox combos is difficult but doable. Unfortunately, Fox can make himself really hard to punish for misstepping or being outplayed during his punish. Sheik leaves more vulnerabilities (because she does her comboing on the ground, mainly, with ground moves). Accept this and move on - you need more precision for certain links or you'll die. Oh well. In exchange, Fox's high KB attacks often makes his extended links (barring shine and nair chains) dry up after 50% or so and this places emphasis on option covering & reading for him whereas Sheik can usually continue tech chasing or keep going with her large array of launchers.
SDI is key vs his multiple-hit moves and the shine. On drills, SDI through him if has a lot of momentum going at you. On stationary ones SDI away. If you perform a good SDI on a dair, you can often counterattack him. Grab is ideal, but d-smash and co. are easier & often just as appropriate (consistency with your plays will win you games).
On horizontal chains (Nair, Bair) it can be worthwhile to SDI in and up to force him to do a vertical combo. Your ultimate goal is to DI away on something horizontal without momentum. Even on DI down and away, because the momentum aerials track DI so well you will almost be comboed further (barring really good SDI).
<<<This space is reserved for Fox's u-throw and what you can do about his 3 main options out of it at low percent, and his 3 main options at medium percent. High percent is basically, "Attempt SDI on uair, survival DI on bairs. Don't be predictable during free-fall and see if his movement tells you anything about what he's trying to punish.">>>
On up airs you benefit from knowing a few things. One, SDIing to the side is better at low percents because his FJ height makes the uair meaty as hell, so SDIing to avoid it vertically is a horrible idea. Two, Fox has legit 2nd uair FJs if you DI the throw to the side at 80-95ish. Third, SDI up escapes works best when his uair barely reaches you (high percent). Finally, DIing the throw behind and DIing the uair the opposite way maximizes distance between you and is a pretty standard combo damage mitigation strategy.
When hit offstage high, falling to the edge with good drifting is strong. Be ready to fair shine spike attempts. You don't have a real answer aside from outranging it or air-dodging through it. You could also attempt a janky up+B. Not a great go-to (as a primary option) but sometimes viable. No lag high poofs force Fox to behave differently and often use hard moves - it's hard to shine the low landing lag version. Just beware of them u-tilting or similar - you won't get your jump back and that brings a huge risk.
When hit off low, sometimes just poising onstage "safely" is a good option because combos are DIable and losing a low percent stock is huge gamble. Pull away with your DJ to outspace offensive shine spikes. Rambo defensive, coverage strats if you can reach Fox - if not, use your best judgment. A lot of people are still bad vs the double explosion landing recovery so always keep it in mind. Especially if you notice shoddy invulnerability storage. If they like to release the edge to cover non-sweetspot poof angles & landings, try very hard to get that sweetspot by any means necessary (you sweetspot by skipping the white explosion with no hitbox - do this by aiming down + towards the edge [sideways produces the white explosion]). You will sometimes be kill-maimed here but such is Sheik's recovery.
Recovering onto platforms is okay for guaranteeing extra recovery height. It's not hard for Fox to 2nd hit uair you in that position though. It also denies him conventional shine follows. Usually a good choice. Be ready for drill-grabs and other shineless setups.
Ground tech is important to survive d-smashes, helps you survive bairs & f-smashes, and is useless vs shine, uair, grab, and u-smash. Strong normal DI & SDI can often suffice until very high percents (except vs d-smash, which can loop vs Sheik at really dumb percents if you can't ground tech it because of the trajectory).
Edgeguarding for Sheik on high Fox recoveries can be treated similar to how she swats them in the neutral. Jumping and aligning yourself with them is a good cover for illusions - just bair or nair if you hear the 'ding'. Then follow up until they're sufficiently dead.
Unfortunately, onstage strategies like this that counter the illusion defensively can run into issue with firefoxes. There isn't a perfect answer. You can still usually cover a good chunk of his options by waiting & hitting him out of high trajectories with bair or whatever (I sometimes go for combos because if I hit him before he lands you just need to combo a jumpless Fox to take the stock). And you can cover lower ones by protecting the edge.
If you recognize the firefox quickly you can rambo him with fair or RNS bair too - this is good because they're big moves and the closer you are to Fox's firefox you are, the more his options shrink (angles don't shift his position as drastically). Because of this, many players (M2K and myself included) often take to ramboing him offstage as the default. However, Fox falls faster than Sheik and RNS bair has startup so he may slip by with illusion. Or jump out of your bair's reach and firefox. If you notice him doing that or going low to counter aggressive aerial, abort the mission. Grab the edge and do a typical ledgehop bair edgeguard (or similar) until he's the appropriate amount of dead.
On low recoveries, weak ledgehop bairs and needles cover so much it's dumb. You can do other stuff like... let Fox pass the lip of the stage in some positions (harder though 'cuz Fox sweetspot technology is strong) and time charge d-smash, fair, etc. but bair & needles will cover 80%+ of low recovery situations. Fairing him into the stage is okay at 37%- or so (when fair puts them below 50% there's not enough KB to let them tech it, and it forces them lower than weak bair, so it's a really strong tool).
If Fox likes to hover just above Sheik's height offstage, or around Sheik's height, be ready to tilt, d-smash, nair, bair, or needle the action. This may sound dumb, but d-smash hits low. A lot of the time they're trying to go above that move specifically. Also, f-tilt takes time to reach its full vertical swing - for this reason, alternatives like nair and such are good to keep in mind. Needles vs needle-height opponents (or those going for the edge) are less good than they used to be in 2008 or so because spacies have gotten better at SDI up into illusion / air-dodge but all that means is throw a bunch or make sure you can follow up on it (I needle > jab > d-smashed Mango to counter the SDI once - there are other options too). Like with high recoveries, be ready to switch to offstage rambo mode if they firefox (or pick between covering the edge area or covering the free-fall zones if you recognize the firefox too slowly).
Run off DJ (sometimes delayed) nair can be a good generic cover for a bunch of stuff. As always, picking up on habits makes this much easier. And remember Fox wants to screw with your timing as much as he can - be ready for stalls and low dives. Stalls can be countered by skipping the DJ and falling on top of him. Low dives are beaten by aborting and turning it into a basic low edgeguard.
I do not endorse the chain for anything. Especially edgeguarding. It's vulnerability to SDI hurts it more than most realize. Moreover, there are more effective ways to edgeguard for damage that also often lead to kills (dair comboing a jumpless Fox is really easy).
Knockdown percents contributed by the lovely and talented Strong Bad:
Tumble hitstun AKA knockdown %'s against Fox with Sheik's relevant moves as determined by KirbyKaze. NTSC is assumed.
Fresh = never landed any hitbox of the move within the last 9 moves used.
Stale = hit with the move in all 9 stale moves slots. Just an upper range on when the move would knock down if you were really spamming it.
Percents are for BEFORE the move hits. I didn't do decimals because that's horrible/useless and would take even longer than this already tedious task.
Move | Knockdown (Fresh) | Knockdown (Stale) | CCing Knockdown (Fresh) | CCing Knockdown (Stale)
Dash Attack (Strong) | 20% | 24% | 61% | 66%
Dash Attack (Flub) | 59% | 62% | 114% | 117%
Ftilt | 24% | 27% | 80% | 83%
Utilt (Hit 1) | 43% | 47% | 85% | 88%
Utilt (Hit 2) | 63% | 65% | 123% | 124%
Dtilt | 40% | 44% | 103% | 106%
Fsmash (Second hit) | 16% | 21% | 76% | 80%
Usmash (Weak) | 7% | 13% | 41% | 47%
Dsmash (First hit) | 19% | 25% | 61% | 67%
Nair (Strong) | 35% | 41% | 66% | 72%
Nair (Early Flub) | 55% | 60% | 97% | 101%
Nair (Weak) | 62% | 66% | 107% | 111%
Fair | 39% | 45% | 72% | 78%
Bair (Strong) | 26% | 32% | 57% | 63%
Uair (Strong) | 21% | 26% | 51% | 56%
Uair (Weak) | 37% | 41% | 75% | 79%
I didn't do Fsmash 1st hit because it never tumbles against any character unless they're currently charging a smash and are Fox's weight or lighter (lol), where it tumbles at 0% because it's set knockback. If you want tumble % for if you hit with both hits of fsmash, subtract 4-5%ish from the % listed.
I didn't do other variations of Bair because that move has literally 7 different possibilities for knockback values and I'm just not doing that. LOL.
If I were to do this against another character/for another character, I'd make a spreadsheet specifically for it. Doing trial and error with victim damage for everything was very tedious. x_x It took me like an hour.
