Playing as Sheik -- dealing with Pit
Sheik was my main in Melee, and is still one of my top now. One of my friends plays Pit--- and God is he good at aiming those arrows...
To be honest, I find the match up to be pretty well in Sheik's favor. Here's what I suggest:
•Use your Ftilt to combo him (I recommend using it twice, then shield-grab him) then throw him and chase.
•Sheik's aerial power lies in her Nair, Bair, and Fair (her Uair isn't bad either, It's just not as effective as it use to be. It can however, be a good finisher if the opportunity arises). I suggest that after a series of Ftilts, once Pit is suspended a bit in the air from the attack, jump and do a Nair, which comes out nearly right away. You could also do a Fair and chase him doing more Fairs in succession.
•Sheik's Usmash is a good finisher, along with her Dsmash. Sometimes her Fsmash doesn't hit with both kicks, otherwise it's usually effective. All of Sheik's comboing potential comes from her tilts. As I've mentioned Ftilt is amazing, as it is so quick, with no lag, and comes out before most enemies have a chance to respond from the attack. It's also worth noting that her Utilt is very good as well.
•Using your needles is helpful, as some have pointed out. Try charging them if you have a chance, if not, single needles will suffice. Though, against a character like Pit, chances are his arrow will be more annoying than your needles. So forcing him to come to you via needle spam is unlikely as his arrows probably out-prioritize them.
•Keep in mind one of Pit's greatest weaknesses: His ^B can only be used once. The greatest aspect of Sheik in Brawl, is the addition of her chain as a tether. Also, the fact that you can use your chain/vanish independently is a huge plus (one doesn't have to worry that if the chain doesn't reach the edge they are dead, because they can still vanish after using the chain tether). In my opinion, vanish should never be used as a recovery, the chain is just too good. Sheik's edge-guard game is amazing.
After you chase an enemy off the edge attacking them with aerials, you can very quickly tether to the edge. Tethering also allows for a lag-less instant recovery unlike any regular recovery. This means that one can immediately go from tethering the edge to attacking, jumping, or rolling. This is great for Sheik because she's now an incredibly versatile character. I think you also have a few frames of invulnerability due to the fast recovery.
What I do when edge-guarding with Sheik is chase the person off with any aerial attack, notably Fair, then I tether to the platform, and immediately go after them again after having renewed my jump, then I repeat. It makes for a mean edge-guard, one unlike most every other character in the game.
Now why is edge-guarding so stressed here? Simple, due to Pit's inability to execute a second ^B, he is extremely easy to gimp. Just keep on him, as soon as his springs forth his wings, make sure you hit him, at this point his only chance of survival is DIing to the nearest ledge. His chances of DIing anywhere near a ledge will be slim, especially because you have a tether recovery. You can beat him and most other characters to the edge.
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Sure Sheik is different in Brawl than in Melee. In Melee she had amazing kill moves, especially her Fair. She's still VERY good now, if anything, she is underrated. It seems that many people fail to recognize her comboing potential (Ftilt) and her amazing edge-guard potential. To be honest, without her tether recovery, she'd suck in Brawl. Her tether single-handedly makes up for anything she lost in Melee.
In addition, the fact that she can wall-cling and crawl are also useful given the scenario.