On Wiki General Great base 127 Speed and good 120 base Special Attack Serene Grace gives its Seed Flare an 80% chance to lower Special Defence by 2 stages, making it very hard to wall It also gives Air Slash a 60% chance to make the opponent flinch Its typing allows it to check Groudon, Kyogre and Tyranitar Weak to Stealth Rock Very frail Movesets SubSeed Nature: Timid (+Spd -Atk) Item: Leftovers Ability: Serene Grace EVs: 252 SAtk, 4 SDef, 252 Spd Substitute Leech Seed Air Slash Seed Flare Designed to frustrate and annoy Leech Seed allows it Recover lost health, and whittle opponents down Air Slash has a 60% chance to make the opponent flinch, granting further recovery by Leech Seed Seed Flare's secondary effect makes it very hard for foes who don't resist Shaymin-S's STABs to wall it The EVs maximise speed and special attack. It's a waste of time running anything else due to Shaymin-S's frailty Leftovers and Leech Seed give Shaymin-S good recovery Although the moves are resisted by a fair few Pokemon, their secondary effects make them too good to pass up Life Orb Nature: Timid (+Spd -Atk) Item: Life Orb Ability: Serene Grace EVs: 252 SAtk, 4 SDef, 252 Spd Seed Flare Air Slash Earth Power Hidden Power Fire/ Hidden Power Ice/ Growth Designed to be an all out attacker and late game sweeper Seed Flare and Air Slash get STAB, and brilliant secondary effects Earth Power badly injures Dialga, Jirachi and Heatran Hidden Power Fire hurts Ferrothorn, Forretress and Skarmory. Hidden Power Ice hurts opposing Shaymin-S, Rayquaza and Thundurus. Or you could opt for Growth, which forgos coverage for the ability to hit much harder. In sun, it gives Shaymin-S a +2 boost, skrocketing its special attack to a whopping 678. EVs maximise speed and power Choice Nature: Timid (+Spd -Atk)/ Modest (+SAtk -Atk) Item: Choice Scarf/ Choice Specs Ability: Serene Grace EVs: 252 SAtk, 4 SDef, 252 Spd Seed Flare/ Leaf Storm Air Slash Earth Power Hidden Power Fire/ Hidden Power Ice Utilising its unique speed tier to be either a revenge killer of wallbreaker Serene Grace helps with both roles: Air Slash's Flinch rate combined with Choice Scarf allows Shaymin-S to flinch its opponents to death; Seed Flare's special defence drops make muscling through walls that much easier. Seed Flare is generally the better option, although Leaf Storm is an acceptable alternative for the increase in power and accuracy Air Slash is the secondary STAB Earth Power hits Dialga, Jirachi and Heatran Hidden Power Fire hits Ferrothorn, Forretress and Skarmory. Hidden Power Ice hits Rayquaza, Garchomp and Thundurus. EVs maximise Speed and power Both natures are viable. Modest is recommended for Choice Scarf, since it still outruns 252 Spd Jolly Deoxys-S while hitting noticeably harder. Timid is recommended for Choice Specs, although Modest is an acceptable alternative for the extra power. Other Options An offensive Cleric set with 3 attacks + Healing Wish or Aromatherapy is possible. If that's what you want, use the Life Orb set's setup Hidden Power Rock can be used for Ho-Oh, although its utility pretty much stops there Synthesis can be used, although the weather fluctuations in Ubers make it unreliable Synergy Rock Arceus resists Fire and Flying moves, and in a Sandstorm is bulky enough to take unboosted Ice Beams. It can also take out Ho-Oh. Shaymin-S returns the favour by being able to remove Groudon, Kyogre and Ferrothorn (Air Slash is a clean 2HKO after Seed Flare's stat drops). Tentacruel can Spin away the Stealth Rock Shaymin-S hates and in turn lay Toxic Spikes to make the SubSeed set's job easier Kyogre can take out Ho-Oh and negate Shaymin-S's Fire weakness Dialga is neutral to Fire and Ice moves and resists Rock. It can lay Stealth Rock to help sweeper sets too. Checks and Counters Ho-Oh can usually take anything it has to give and OHKO with Brave Bird or Sacred Fire Reshiram can toast it with Blue Flare, although must watch out for Earth Power Chansey, Blissey and Ferrothorn can wall it if they escape Seed Flare's stat drops ExtremeKiller Arceus can revenge kill it with Extremespeed, although will still take heavy damage from Seed Flare Swords Dance Rayquaza is in the same boat, although has to be more careful switching in in case of Hidden Power Ice In a Sandstorm Rock Arceus can revenge kill with Judgment or Stone Edge, but can't switch in since Seed Flare is a 2HKO.