Moves
Dragon Dance allows Jangmo-o to boost its Attack and Speed, helping it sweep. Outrage is used to clean when foes are weakened; a boosted Outrage 2HKOes top-tier threats like Timburr, Vullaby, and Mienfoo. However, it is not optimal to be locked into, as the opponent can exploit this and switch in a Dragon-resistant or -immune Pokemon to set up on Jangmo-o. Alternatively, Dragon Claw can be used if you do not wish to be locked into a move, though the power difference is noticeable. Earthquake allows Jangmo-o to hit Fairy-types neutrally while hitting relevant Steel-types like Alolan Sandshrew and Magnemite, which resist Jangmo-o's STAB attacks. Brick Break hits Ferroseed super effectively and guarantees an OHKO on Pawniard. However, Substitute allows Jangmo-o to set up safely by shielding it from moves like Spore and Will-O-Wisp from Pokemon like Foongus and Pumpkaboo-XL, respectively, which would otherwise cripple it.
Set Details
236 Speed EVs allow Jangmo-o to hit 14 Speed, outspeeding the entire unboosted metagame after a boost. 236 Attack EVs with an Adamant nature allow Jangmo-o to reach 15 Attack, thus making it hit as hard as possible. Berry Juice is the ideal item for Jangmo-o to regain health, support its sweep better, and also heal back Substitute damage. Bulletproof allows Jangmo-o to set up on and check Gastly and Croagunk; alternatively, Overcoat allows it to dodge Foongus's Spore and any other powder move.
Usage Tips
Jangmo-o should be sent out when Fairy-types like Snubbull and Spritzee and Steel-types are weakened, as well as when bulky foes are down or have their items Knocked Off. Don't lock Jangmo-o into Outrage until Fairy- and Steel-types are eliminated. Come in on bulky status inducers, create a Substitute, and then set up, as they can hinder Jangmo-o's sweep. Setup opportunities for Jangmo-o are limited, so create a Substitute on forced switches, such as Croagunk and Magnemite locked into Flash Cannon. Jangmo-o can set up or create a Substitute on Pokemon like Gastly and Foongus, as it resists their STAB moves, and Jangmo-o can use Substitute on a predicted Spore from the latter. Jangmo-o mustn't attempt to set up on faster, powerful Pokemon, such as Doduo, Abra, and Mienfoo, as it will usually be KOed due to its poor defenses.
Team Options
Jangmo-o fits well on bulky offensive teams, as it appreciates foes being weakened for a sweep. Steel-types are great partners for Jangmo-o, as they can take on Fairy- and Ice-types that Jangmo-o is weak to. Pawniard, for example, can punch holes in the opposing team for Jangmo-o with Swords Dance and Knock Off. Poison-types like Gastly and Foongus in general are effective at removing Fairy-types. Bulky pivots like Vullaby and Chinchou work well with Jangmo-o, bringing it in for free. Wallbreakers like Corphish can punch holes for Jangmo-o and allow it to sweep more easily late-game. Jangmo-o hates being worn down by entry hazards, as its only form of recovery is Berry Juice, so Pokemon like Staryu and Vullaby make for good partners. On the other hand, Jangmo-o loves entry hazards on the opposing side to wear down the opposition, so Onix, Dwebble, and Omanyte make for great partners. Knock Off users, such as Pawniard, Vullaby, and Mienfoo, can help to remove opposing Eviolites and help Jangmo-o break past foes more easily. Diglett traps the Steel-types that prevent Jangmo-o from spamming Outrage.