I half a build for shedinja, but it can't learn swords dance...
Shedinja@focus sash
Adamant nature
252atk 252spd
X-scissor
Shadow sneak
Will-o-wisp
Don't know what to put
Also a zoroark I have in the same team.
Zoroark@
Modest nature
252sp.at 252spd
Dark pulse
Nasty plot
I don't know what other moves to put, or an item.
Shedinja needs a lot of support to even function effectively, mainly getting hazards off the field so it can come in unscathed. In Gens III-IV, Shedinja comes with the moves that Ninjask has upon evolution; this isn't the case in B/W/B2/W2/X/Y, when it comes with the moves that Nincada had, so the only way for Shedinja to have Swords Dance or Baton Pass in Gens V and VI is to transfer a Gen III/IV Shedinja from Poke Transfer:
-Shadow Sneak
-Protect
-Will-o-Wisp
-Baton Pass
Nature: Brave
EVs: 252 Atk
Item: Lum Berry/Focus Sash
or
-Swords Dance
-Shadow Sneak/Shadow Claw
-X-Scissor
-Will-o-Wisp/Protect
Nature: Adamant
EVs: 252 Atk/252 Spe
Item: Lum Berry/Focus Sash
Zoroark must always use a Timid nature because it's outsped by neutral base 100 Speed Pokemon otherwise:
-Nasty Plot
-Dark Pulse
-Flamethrower
-Focus Blast
Nature: Timid
EVs: 4 HP/252 SAtk/252 Spe
Item: Life Orb/Focus Sash
Is this tier X/Y OU? If this is so, Mega Blastoise, Excadrill and Forretress are good Rapid Spinners for you to include:
Mega Blastoise:
-Water Pulse/Scald/Hydro Pump
-Dark Pulse
-Aura Sphere/Ice Beam
-Rapid Spin
Nature: Modest
EVs: 252 HP/252 SAtk/4 SDef
Item: Blastoisnite
Excadrill:
-Earthquake
-Iron Head/Rock Slide
-Rapid Spin
-Stealth Rock/Swords Dance
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Chople Berry/Air Balloon
Ability: Mold Breaker
or
-Earthquake
-Iron Head
-Rock Slide/X-Scissor/Shadow Claw
-Rapid Spin
Nature: Jolly/Adamant
EVs: 4 HP/252 Atk/252 Spe
Item: Choice Scarf
Ability: Mold Breaker
Forretress:
-Stealth Rock
-Rapid Spin
-Gyro Ball/Earthquake
-Volt Switch
Nature: Relaxed
EVs: 252 HP/252 Def/4 SDef
Item: Leftovers
Ability: Sturdy