Whatever you do, don't sit in Shield. Marth's oos options are okay at best, with Dolphin Slash being punishable on hit at early percentages.
If you do find yourself stuck in shield, only shield grab if Sheik is directly in front of you since she can space to avoid it. once again, Dolphin Slash can be a good option, but we have retreating oos nair as well.
Even though Sheik has superior mobility, always try to stay moving. Remember that we have the best walk in the game and to use it for micro-spacing. Forward tilt and up tilt are our friends and will beat out almost all of Sheik's melee arsenal. Jab is also great for stuffing out approaches, but if it whiffs you will get punished.
Maintaining stage control is paramount. Sheik excels at pressuring and if she can back us to the ledge we will find our options severely limited and fast. Try to stay close to the center of the stage while keeping Sheik towards the ledge. try to look out for and rpedict how she will try to get past you and swat her away. Remember that the potential threat of a large disjointed hit-box can be just as potent as one being out.
Do not let Sheik charge needles. If she's in a position where she can start charging and firing them freely, you are going to have a very bad time. Sheik running away from us isn't what's important since it's really bad when she is too far inside our range, as long has she doesn't get too far away to start needle shenanigans. It's all about spacing.
Looking all the way back to Melee, going into the air is usually a bad idea. We've all seen the gif of Sheik's fair versus Marth's fair by now, so that's pretty self explanatory. if you are jumping, it will usually be backwards to escape something or going over needles. Full hops aren't to useful outside of combos and juggles.
One of the most important things to remmeber in this MU that
DariusM27
touched on is don't panic if you are being combo'd. At early percentages her combos will not likely lead to kills nor kill set-ups. Sheik can't get kills if we don't let her. Everything she has as a raw kill option is slow and require set-ups that look to bait air-dodges and are always DI dependant. Until raw fair kills at really high percents, just stay calm and patient and remember to mix it up. After the low percent,s almost everything will be Di dependant. Head on over to the Sheik boards and research what is true and what is es-capable. It's crucial information and WILL save you.
The scariest thing Sheik has in her arsenal that will end you are needles to Salmon, which is true at higher percents no matter what. Remember to not give her the space to charge them.
Edge-guarding. Sheik fair versus Marth's fair gif not withstanding, We have few reliable options for dealing with Sheik's recovery off-stage. Vanish cannot be countered and trading aerials isn;t always pleasant. Our most solid option outside of predicting her ledge get-up is to punish the vulnerable frames of her ledge-snap out of Vanish. practice this and practice it good.
A good way to practice this is to go into training mode and put a CPU Sheik off-stage. Pausing the game will prevent CPU from acting and once it's low enough you can un-pause to force it to recover low to the edge. Just practice hitting it with whatever until it's second nature.
On the flip side, the only character that edge-guards harder than Sheik imo is Pikachu. Sheik has so many tools for knocking us out of our recovery that are quick, effective, and hard to contest. Run-off Vanish, Slammin' Salmon, needles, needles into Slammin' Salmon, literally any aerial (even dair, that s*** spikes and is hilarious when it does) but most prominently bair. If you're going to contest anything, use nair since it has great range and two hits, unless your two low that putting out an aerial would prevent you from reaching the stage. Counter is good if you;re certain you will be hit, but keep in mind it's useless against needles and Salmon sicne she will just bouce away before the counter hits her. Mix it up however can and remember that going low isn't quite favourable. If you can reach the ledge by simply using Dolphin Slash, then try for it since if you get knocked out of it you'll still have your second jump.
In terms of stages, we don't have a lot of favourable options. While some stages are definitely better than others
Battlefield might actually be our best pick. While Sheik can use the platforms to extend combos, she doesn't really on platforms to combo very much, meaning we can use them to escape and set-up traps of our own. It also has some of the largest blast-zones of the legal stage roster, so as long as we keep mixing up our di and combo escapes, we can live for a very long time. A solid
Final Destination is more of a gamble, and a mostly unfavourable one at that. Having a lack of any platforms to evade needles or escape combos is mostly a downside for us. Fighting here essentially comes down to being able to keep our back from the ledge while preventing Sheik from needle camping. It's certainly feasible, but definitely uphill.
Smashville is Sheik's best stage. While the stationery platforms are good for her, the one here is a dream since she can use it's moving nature to carry you all the way off into the blast-zone. However, Smashville is one of Marth's better stages as well since it's a little smaller than most others and we are also quite fond of the moving platform. Neutral will go either way here. just try not to get caught out off-stage or on the platform when it's very far to the side. This is a stage that is almost always played on at least once in a set. Know it and know it well.
Town & City is hialrious. it's one of my favourite stages to play on in general. It's sometimes a smaller FD, but will sometimes be like Battlefield with the more extreme elements of Smashville. The ever changing dynamic is completely yours to adjust to, but be wary of the lower ceiling since a lot of Sheik's kill set-ups will take you off the top. However, Sheik can only get those kills if you give them to her, and our up-air, up tilt, and the up variants of Dancing Blade can kill pretty nicely here. If you are confident, this might not be the worst choice.
Duck Hunt is the worst stage in this MU for Marth. it's basically FD with so much more space. If Sheik really wants to she can charge needles easily by going up the tree or too the other side of the stage. I would ban this stage one hundred percent of the time as Marth if not for the other characters I play.
Lylat Cruise is a stage I'm fond of personally. I feel this is one of Marth's better stages since the layout considerably buffs his juggling and spacing game, with f-tilt being able to tip through the platforms. Sheik's juggling and combo game also gets a buff here, but i feel the trade-off in favour is worth it. She can;t run away to charge needles and the platforms mess with Salmon. It's too bad it's almost always banned.
Dreamland is Battlefield. No if's ands or buts about it. Marth will prefer Battlefield for the slight difference in the platforms, but it won't matter too much. What makes Dreamland's addition great is that there is only one ban now, so if Sheik doesn;t want to go to the battlefield layout it won't matter. If she strikes one we can just pick the other. it will be especially useful if we've exhausted our Lylat pick due to Dave's Stupid Rule.
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An unarguably unfavourable match-up. The amount of effort we have to put in is almost heartbreaking, but it isn't entirely unfeasible. We'll probably never see a Marth overtake a high level Sheik, but we still have options and tools at our disposal that will work.
I say the Sheik match-up is 70-30 in Sheik's favour.
