Moves
Baton Pass is the safest switching move that Shedinja can use, as the only thing that stops it from working is the move Taunt, which is quite uncommon. Other switching moves all rely on your opponent not having a common item, type, ability, or move, such as Rocky Helmet, Ground-types with Mold Breaker, and Magic Bounce users, all of which can spell trouble for your Shedinja. Pain Split shares the difference between Shedinja's HP and its foe's; because of Shedinja's hardcoded 1 HP stat, it will always cut the foe's HP in half. It's a slower method of knocking out foes than a move such as Endeavor, but it has the benefit of not making contact and being able to hit Ghost-types. The respectable 32 PP that Pain Split offers also means that any recovery on a defensive foe can be stalled out, securing Shedinja a KO or allowing teammates to sweep it with little trouble. Alternatively, Shedinja can run Endeavor as a more drastic means of attempting to lower the HP of an opposing Pokemon. Whirlpool complements both Pain Split and Endeavor very well, as it deals damage equal to one-eighth of the foe's maximum HP at the end of every turn while also preventing them from directly switching out, aside from Ghost-types and Shed Shell Pokemon. Whirlpool is less accurate than Infestation, but it has the benefit of not making contact, meaning that Shedinja is not vulnerable to the effects of Rocky Helmet, Spiky Shield, and abilities such as Rough Skin. Partial trapping is vital on this Shedinja set if you intend to score KOs with it, especially with Pain Split, as Pain Split can only do so much damage before it ceases to work. Safeguard and Recycle are both moves that reduce the risk of status knocking out Shedinja, and the move used depends on Shedinja's item. Safeguard works with Safety Goggles to give Shedinja an immunity to status as well as to residual weather damage, but even the turn used to set up Safeguard can be very risky for Shedinja. Conversely, Recycle allows a Lum Berry to be used up to 16 times, making Shedinja virtually immune to status but leaving it vulnerable to weather damage and forcing Shedinja to go on the defensive when facing a foe that spams status moves. Another option is Shell Smash, which can be used in conjunction with Baton Pass to pass very powerful stat boosts to Shedinja's teammates.
Set Details
Shedinja being Level 1 allows for a slow Baton Pass to ensure that you start the next turn with the upper hand; this Shedinja set will almost assuredly go last, except against other Level 1 Pokemon. Furthermore, the minimalized defenses guarantee that your team will be able to OHKO any Imposter Pokemon that copies this set, provided you have a Pokemon with Mold Breaker and Pursuit on your team. Even if not, many opponents don't pay attention to Shedinja's level, so they don't consider that their Imposter users will have only single-digit defenses after they transform, increasing the likelihood of opponents keeping their copied Shedinja in on any Pokemon that doesn't look like it will OHKO them. Safety Goggles provides Shedinja with the ability to avoid passive damage when supported by teammates with Aromatherapy or Heal Bell, allowing it to not be bothered by the occasional sand or hail team, as well as supplying a useful immunity to the omnipresent Spore. Lum Berry, on the other hand, allows Shedinja to run more independently in regards to status when paired with the move Recycle to keep status away without switching out, with the compromise being that any sand or hail team will render Shedinja useless, as it will be knocked out as soon as it switches in.
Usage Tips
Above all else, this Shedinja set is a defensive pivot, so Baton Pass should really be the only move it uses to minimize the risk of it fainting and compromising your team's defensive synergy. However, Shedinja shouldn't be the only Pokemon capable of taking a hit on your team, as the methods of dealing with it are flexible enough to be applied to any Pokemon, sweepers and walls alike. If another Pokemon on your team is capable of taking a hit or two from a certain threat, switch into that before switching into Shedinja, as it will give you the opportunity to find out what moves the foe is running and whether or not Shedinja should be afraid of them. Directly switching into Shedinja should only be done when you know what your opponent is running or when no other Pokemon on your team is capable of taking a hit from a certain threat.
Furthermore, the use of slow switching strategies on Shedinja's teammates makes scouting for Shedinja's checks a lot easier. A slow switch into Shedinja not only keeps Shedinja safe from any attacks but also allows you to see whether or not the Pokemon you're facing is capable of dealing with Shedinja. Oftentimes if a certain Pokemon can't either KO or outheal Shedinja, it will switch out immediately. Shedinja will be able to safely Baton Pass away afterwards, and for the rest of the match you will know almost for sure that that certain Pokemon can be checked by Shedinja. Be wary of Mold Breaker and its clones, which anything can run in Balanced Hackmons. You want to keep Shedinja alive as long as possible; don't just sacrifice it in the beginning of the game because you see an opportunity for a KO.
Team Options
Shedinja's niche isn't hampered by many playstyles or team setups, so it is able to find a place on most teams. However, Shedinja isn't something that can be thrown on a team for an instant win; if you don't want Shedinja fainting very early, a large part of your team needs to be built around it or at least optimized for use with it. Use Shedinja alongside a Mold Breaker Pursuit Pokemon such as Giratina or Mega Gyarados to lure opposing Imposter Pokemon into your pivoting Shedinja and OHKO them every time. Entry hazard removal is mandatory. Defog is the most reliable method, although Rapid Spin can be run if you're looking to only remove hazards from your own side of the field, though it can be blocked by the many Ghost-types in Balanced Hackmons. Common Defog users include Registeel, Aegislash, and Lugia, but the move can be run on just about any defensive Pokemon with success. Rapid Spin is usually reserved for Pokemon that run Assault Vest + Regenerator, which can include Regirock, Registeel, and Kyogre. Status curing is also very important, especially if you run Safety Goggles. Not only do the moves Aromatherapy and Heal Bell allow Shedinja to switch in after it's been inflicted with a status, but they also cure other members of your team. These moves can usually fit nicely into the moveset of a Pokemon that uses Defog, particularly ones with the Prankster or Magic Bounce abilities. To reduce risk, it's a good idea to have an Imposter teammate to scout the opponent's movesets before bringing Shedinja in on them if possible. Chansey is the best choice. Scouting can also be achieved by using VoltTurn strategies to determine the movesets of the opponent's team. The use of defensive Pokemon with Regenerator alongside Shedinja nullifies residual damage from Leech Seed and partial trapping that gets passed by Baton Pass, assuming they switch out afterwards, as well as providing an opportunity for these VoltTurn strategies. Pokemon such as Mega Slowbro, Regirock, and Registeel are often effective users of Regenerator.