Frustrated by the complaints that Sheik is "different" as if it wasn't intentionally made so, I have compiled up this list of Sheik changes for the public to read and study so they know how to use her modified moves in P:M. In particular, the dthrow/bthrow mixup.
D-throw - Uses a PAL-like angle of 62 instead of 80, so there are no longer unavoidable dthrow chains or aerials every time this throw is used. However, it launches the enemy twice as fast as it did before so there's less time to react to it. If the victim could be comboed by Dthrow in NTSC Melee, they will be comboed by this throw unless they DI directly away from Sheik. Neutral DI allows dash attacks, Fair/Nair, and regrabs. Inwards DI allows a deadly Usmash tipper.
B-throw - Has higher BKB and lower KBG. Uses a higher angle of 67 instead of 45. If the target DIs away to avoid Dthrow combos, Bthrow will punish that DI and put them in a perfect spot to follow with a regrab, dash attack, aerial, or even an Usmash KO depending on % and floatiness. Even fast fallers like Fox and Falco can be comboed outright following this throw if they DI it towards Sheik, a possibility not seen with the default Bthrow. At the edge, this can lead to a simple run-off Fair for the kill.
It is important to mix up Bthrow and Dthrow and condition your opponent into failing to DI the right throw properly. Like Fox and his Uthrow, it is beneficial to you to use your intended throw right when you grab for speed purposes.
Rapid Jabs - are rather usable in this game. Their attack rate is higher and they're not as easily cheesed through SDI. They're not entirely abusable, however, as fast and ranged attacks can hit Sheik before she recovers from rapid jabbing them even if done for as briefly as possible. This is easily seen with targets that can quickly DI away and down from the move.
F-smash - is actually decent. The first kick's KB is much more conducive into comboing into the second, and is not ASDI-CCable. The second kick has a higher launch angle, less KBG, and slightly less afterlag. This allows it to combo into something else at low percents, and also at high percents (DI depending). Combine with a stutter step to increase its range for distant punishment.
Needles - they are not as effective as they used to be in Melee due to them being clankable hitboxes without their own hurtbox articles in this game. In Melee, they are unclankable, but have hurtboxes placed deeper inside the move's hitboxes. It was these hurtboxes that needed to be hit to cancel out the move, and their deep placement was the reason they were difficult to clank out in Melee. Needles are still great projectiles with a lot of utility and deadly land cancels. Just don't be surprised when an opponent is able to cancel out multiple needles, or even all 6 of them at once with their own attack. This is not intentional behavior, and will be addressed when a viable solution is found.
If Sheik has any needles stored but is KOed as Zelda, you will lose the needles even after changing back into Sheik unlike Melee.
Chain - Unlike Melee, the chain's hitboxes are unable to clank out projectiles. The electric tipper hit also cannot hit aerial targets, so the effective range is reduced somewhat against people in the air. Brawl mechanics have blessed the chain with the drag maneuver though, which allows the hitboxes to refresh very quickly when the chain is maneuvered with a repeated 2323_2121 motion with the chain flat along the ground. This can deal a great amount of damage in very little time, especially if they dare attempt to CC their way out of it.
Like Melee, the chain also has two different sets of hitboxes for ground and for air use. The air hitboxes have more damage + BKB and actually stop the opponent in their tracks when hit. The air hitboxes can be preserved in the ground state by jumping, using the Chain, and landing after the chain is generated, but before it fully extends. It can build a very effective wall at the edge against certain recoveries, or force an opponent's rush into a hasty retreat to escape Chain combo damage. The ground chain's hitboxes have very little hitstun and lower damage, but are more conducive to the chain drag trick against non-CCing targets.
The chain jacket glitch still exists, and like always is particularly effective when used in conjunction with Dsmash.
Vanish - The damage/KB is Brawl's, so it has some capacity to KO. During the initial jump Vanish does when used in the air, it can grab the edge backwards without warping. You can Vanish and direct the warp facing backwards towards the edge to grab it as per the universal reverse grab mechanic, but you will always be vulnerable for a frame before grabbing the edge this way. Unlike Zelda, Sheik has to warp the full duration before she can grab the edge backwards with her UpB.
Transform - is a valid special move due to the efforts in making Zelda be able to compete. When you use it, you're vulnerable for 62 frames before triggering the loading phase for Zelda. During this time you can be attacked and prevented from transforming. When the loading phase is triggered, you're invulnerable to attack until Zelda is loaded. When Zelda appears at the end of the loading phase, she can act instantly. Attacks can also be buffered out of Transform to guarantee they will hit as fast as can be made possible. This discourages people from simply camping her location to attack her when loading the other half, the load time being subject to random inconsistency. These traits are also shared by Zelda's transformation into Sheik.
Transform can be used offstage to take advantage of Zelda's better horizonal recovery. If you are knocked far offstage but are decently above the level of the stage, Transform, buffer Zelda's aerial jump towards the stage, then UpB to recover better than Sheik alone would have been able to. Using Transform this way requires SD load times to be reasonably quick, or the act of using Transform offstage might just kill you.
Since the loading phase of Transform renders Zelda/Sheik's hurtboxes nonexistent, it can also be used to detach a sticky C4 by Snake. No other character in the demo can currently do this.
Another small fact is that while Zelda's Transform retains horizontal momentum when performed in the air, Sheik's does not.
Crawl - Sheik retains this ability from Brawl. Since Sheik's crouch is quite low, this is one of the better crawls in the game, perhaps second only to Snake's. Crawling under an opponent's projectile to close the gap and avoid the projectile is a standard use of crawl. There are other, situationally effective uses so don't forget she can do this.
Wall Cling - very situational even in comparison to crawl, Sheik also retains the ability to wall cling. Aside from stages that have very obvious walls, this can also be used in the small corners of FD along its sides. While clinging, you can wall jump, let go, or even aerial jump straight up by pressing the jump button while still holding towards the wall. This is usable even if you had used your double jump already before landing, but utilizing the wall jump from a wall cling will not grant back your aerial jump if you had already used it. Wall cling can be used to set up Fair edge from more threatening locations with easy timing, or to mix up how you attack from the ledge, as wall clinging after a ledge drop reverses direction and allows the use of Bair. Ledge drop, wall cling, then either jump straight up into a Bair to attack or UpB from the wall to reverse grab the edge again.
