http://thpp.supersanctuary.net/wiki/Speed_YamameType:
Earth/
MiasmaAbility: Infectious/ Strange Mist
Hp: 70
Atk: 105
Def: 70
SpAtk: 60
Spdef: 70
Spd:115
Yams, Yams Yams Yams, the greatest of root vegetables. With her unique typing and access to perfect neutral coverage, priority, baton pass, and useful setup and status moves this tricky spidery treat is truly delicious.
TailYamsSYamame @ Lum Berry/Leftovers
Ability: Infectious
Ev's:252 Atk/ 52 Spd/ 200 Hp or 252 Atk/ 252 Spd/ 4 Hp
Nature: Adamant (+ Atk,-Spatk) or Jolly (+Spd,-SpAtk)
-Tailwind
-Earthquake
-Poison Jab
-Baton Pass/Steel fist
Yams has a somewhat flexible EV spread, at 52 speed adamant she out speeds +speed nature 140's allowing for more bulk however a 252/252 jolly build allows her to play revenge killer opening up more utility so feel free to tailor her to your teams needs. Steel/Miasma/Ground offers perfect neutral coverage giving yams a very real chance at sweeping unprepared teams all on her lonesome while baton pass allows her to give a tailwind to something absolutely devastating and gives SYamame a way to completely bypass many of her counters.
ChoiceSYamame @ Special Bloomers
Ability: Infectious
Ev's: 252 Atk/252 Spd/4 Hp
Nature: Jolly (+Spd,-Spatk)
-Earthquake
-Poison Jab
-Steel Fist/Rock Bullet
-Pursuit/Rock Bullet
I normally just leave choice sets under options however Yams gets special mention due to her access to both rock bullet and pursuit (the most underused move in the game). With the ability to revenge kill large portions of the metagame via raw speed and priority in addition to the ability to trap weakened but still lethal threats Choiced Yams gains a niche all her own.
Options: SYamame has access to many support moves such as spikes, encore, toxic, spider web, taunt, and even the sub+endeavor+priority combo. However due to her lackluster def stats these roles are better left to her normal and technical forms. Gunk shot is a stronger stab and can
Defile Waifu's net a few borderline ohko's however the accuracy drop isnt worth the power unless your just crazy lucky.
Support: As a pure sweeper SYamame really wants spikes and a bit of damage on flyers and dedicated walls to supplement her somewhat mediocre attack stat. As a baton passer spikes are nifty but the main focus should be on viable pass targets that can cover her weaknesses and wreck havoc on opposing teams while not "needing" tailwind to function. T Byakuren, A Suwako, A Remilia and A Kazami are all examples of potent mon's that become absolutely ungodly with a single tailwind.
Counters: Strong physical walls with both a super effective move and phasing can hard counter Yams all day long, D Tenshi, physical Suika, and D Hatate can all come in and force SYamame out regardless of her set. Powerful bulky attackers such as Magic Stones or detect + speed boost abusers can revenge kill a pure tailwind Yams however one baton pass later and suddenly your while team is just gone so beware. She's also weak to both aqua jet and rock bullet and neutral to other forms of priority so that's always an option however the weaken and revenge strat will leave you open to baton pass.