Moves
Close Combat is Passimian's strongest STAB attack and relatively safe to use. However, it does drop Passimian's defenses with each use, which can leave it vulnerable to being revenge killed by Pokemon it can't KO. U-turn is important so that Passimian escapes bad matchups against Pokemon like Slowbro, Cresselia, Gardevoir, Noivern, and Palossand as they attempt to switch in. Earthquake hits Poison-types such as Salazzle, Nidoqueen, Toxicroak, and Dragalge much harder than its other moves. Rock Slide can be run instead to hit Pokemon that resist Close Combat such as Golisopod and Noivern. Gunk Shot is also ideal for catching Fairy-types such as Gardevoir and Florges and Grass-types such as Virizion and Shaymin off guard. Knock Off is another move to consider, since it removes the items from a defensive check such as Golbat, Sigilyph, and Florges.
Set Details
With a Choice Scarf and proper investment, Passimian can outspeed Pokemon such as Raikou, Salazzle, and non-Choice Scarf Noivern and Speed tie with Choice Scarf Gardevoir. Defiant is the best ability to run to pressure Defog users such as Mandibuzz and Articuno as well as Sticky Web users like Ribombee and Araquanid.
Usage Tips
Passimian's ability to force switches along with its access to U-turn to escape bad matchups is why it is a successful pivot in RU. It may have good bulk, but Passimian should not be used to take powerful attacks because it gets worn down enough by switching directly into entry hazards and even resisted hits. Because of this, try to bring Passimian in as a lead, after a teammate has fainted, or against more passive Pokemon such as Registeel. When making the play to come in against a passive Pokemon, be careful of potentially switching into a status move such as Toxic. Passimian's defensive typing can also be utilized to switch into Pokemon it can tank hits from such as Golisopod, Tyrantrum, and Mega Blastoise. If the foe decides to switch against Passimian, it would be wise to go for a coverage move to catch a predicted switch-in off guard, use Knock Off to remove items from a defensive switch-in, or simply use Close Combat. Although Close Combat is easy to spam, keep the drop to its defenses in mind, as they make Passimian much easier to revenge kill; be mindful of potential defensive switch-ins such as Slowbro, Gardevoir, and Golisopod as well. Knock Off is also a great move to spam throughout the game due to its lack of drawbacks and potential to remove items from defensive Pokemon like Bronzong and Golbat. If the foe is weakened enough, Passimian can act as a cleaner with its Choice Scarf. Because it needs its Choice Scarf to revenge kill and pivot successfully, Passimian needs to avoid Knock Off early- or mid-game. However, Passimian's resistance to the move can be valuable late-game if it can't do much else or has nothing left to revenge kill. Passimian also appreciates Spikes and Toxic Spikes cleared on its side, since it needs to be as healthy as it can to continue to play its part.
Team Options
Passimian's pivoting abilities are greatly appreciated by slow wallbreakers such as Tyrantrum, Bewear, and Gardevoir and setup sweepers such as Raikou, Salazzle, and Virizion. Virizion can also create a Fighting spam core alongside Passimian, while Raikou, Salazzle, and Gardevoir can pressure physically defensive Pokemon for Passimian, making its time revenge killing and pivoting much easier. Entry hazard setters such as Metagross, Golisopod, and Roserade love Passimian's ability to pressure Defog users like Mandibuzz and Mantine. Metagross can also double as a Flying-, Psychic-, and Fairy-resistant teammate for Passimian. Sticky Web setters such as Araquanid and Ribombee can also make Passimian even more threatening by providing extra speed control. On the same note, an entry hazard remover such as Mega Blastoise, Forretress, or Tsareena is a good idea, since they can clear entry hazards away from Passimian's side, allowing it to pivot much more throughout the game. Passimian also needs defensive checks such as Slowbro, Gardevoir, and Golbat out of the way so it can have an easier time revenge killing. Teammates such as Shaymin, Drapion, and Rhyperior can help Passimian with that. A pivoting core can also be considered to allow Passimian's team to gain and keep offensive momentum. Partners like Yanmega, Forretress, and Ribombee can be paired for this reasoning. Ribombee can also lure in Steel-types for Passimian. Pokemon such as Necrozma, Slowbro, and Noivern greatly appreciate Passimian's defensive presence. Clerics like Florges, Diancie, and Vaporeon and Healing Wish users like Shaymin and Gardevoir can heal Passimian in case it has sustained prior damage.