SERPERIOR, lol, I thought this was gonna be easy given Smuggilous Snape's movepool but I'm seeing a rather nice array of movesets people are coming up with...
FYI, Shell Smash/Break does NOT sharply drop both Defences.
Choice @ Choice Specs/Choice Scarf
Perversity
Modest (+SpAtk, -Atk)/Timid (+Spd, -Atk)
4 HP, 252 Atk, 252 Spd
Lead Storm
Hidden Ice Power/Hidden Fire Power
Giga Drain
Wring Out/Glare/Toxic
Yeah, a barren set. Serperior barely has options, but it's apparently its most common set. Obviously, you charge up your Leaf Storms, hope you don't get walled *ferrothorn* and sweep for game. Basically, I'm here to tell you these are Serperior's best options for Choice, so unless you really really really want a fast fast fast Leaf Stormer.
Physical @ Life Orb
Overgrow
Jolly (+Spd, -SpAtk)
252 Atk, 252 Spd, 4 HP
Swords Dance
Leaf Blade
Return
Glare/Taunt/Natural Gift
Again, barren. Pretty much every Grass type out there is getting Swords Dance and Leaf Blade. What Serperior has going for it is 113 Speed and semi-unique Glare and Taunt. Natural Gift is the Physical Hidden Power because...Serperior just doesn't have anything else.
Conservative Physical @ Leftovers
Overgrow
Adamant (+Atk, -Spd)/Careful (+SpDef, -SpAtk)
252 SpDef, 252 Atk, 4 HP
Coil
Leaf Blade
Return/Rock Smash
Dragon Tail/Glare/Taunt/Light Screen
This set on the more defensive of Serperior applications, by forgoing Swords Dance to also boost Serperior's Def. Dragon Tail and Glare are the only moves that benefit from the Acc increase, but they're good support nonetheless. Taunt or possibly even Torment or Leech Seed are always available.
Rock Smash is used to hit Steel-types, but Leaf Blade actually does more even without STAB. Still, the Def drops might appeal to you.
Conversative Special @ Leftovers/Life Orb
Overgrow
Bold (+SpDef, -Atk)
252 SpDef, 252 SpAtk, 4 HP
Calm Mind
Giga Drain/Grass Knot
Hidden Ice Power/Hidden Fire Power
Leech Seed/Taunt/Glare/Reflect
Inverse of previous set.
DualScreen @ Light Clay
Perversity
Calm (+SpDef, -Atk)
252 HP, 252 Spd, 4 SpDef
Reflect
Light Screen
Leaf Storm/Safeguard
Glare/Taunt
Serperior, aside from Leaf Storm spams, plays a very unique form of Grass-type supporter in its ability to use DualScreens, a trait shared with Meganium, Celebi, and Exeggutor. Anyway, it's something, especially given other status moves like Glare or Taunt. Leaf Storm is so that it can hit hard if desires, possibly even setting up for a sweep of its own.
Status Platforming (SubSeeding) @ Leftovers/Big Root
Perversity
Bold (+Def, -Atk)
252 HP, 80 Def, 176 SpDef
Leech Seed
Substitute
Taunt
Glare
I don't have time to research different damage calculations, given my personal time AND how early on it is in Gen 5 AND the fact no one really cares. So I just listed balanced defensive stats to make them 270 apiece.
Anyways, pooling all of Serperior's supporting moves together, you get a bit of a SubSeeding set. Mix and match with any of the moves from "Other Options." Either Leaf Storm or Giga Drain are possible for attacking options.
Utility Attacker @ Miracle Seed/Life Orb
Perversity
Timid (+Spd, -Atk)
104 HP, 252 SpAtk, 152 Spd
Leaf Storm
Hidden Ice Power
Taunt
Glare/Toxic
This is Serperior to sweep with Leaf Storm without the actual need of a boosting move or Choice Item. I have personally created this Serperior for usage in the Ubers environment and I have to say it functions incredibly well.
Tormentor @ Leftovers
Perversity
Jolly (+Spd, -SpAtk)
252 HP, 252 Spd, 4 SpDef
Torment
Substitute/Protect
Wrap
Leech Seed
Serperior has a blistering 113 Base Speed with adequete defences to back it up. Unfortunately, its movepool leaves a lot to be desired, which hampers its Torment set. Still, a hyptothetical set of Wrap + Leech Seed can work. Work with whatever you feel like, possibly even CM + Giga Drain.
Team Options:
On an Ubers team, I utilize Chandelure to combat Fire, Ice, and Steel. Serperior in turn can fight Water, Rock, and Ground.
Otherwise, Serperior loves hazards. In Ubers, it loses out on many OHKOs without it.
Doubles/Triples
Serperior's only appealing category is Speed...and that's about it. It does make for a fast Gastro Acid though, although Gastro Acid has little utility elsewhere.
Other Options
Serperior could possibly try a Growth set, but there are so many better options out there. Besides, Serperior is much more comfortable working its niche: Pb Storm. And if not, Swords Dance. Of course, you could always try playing the Growth set as you would Swords Dance, only with Hidden Power. Like aforementioned, however, there are better Growth users than Serperior.
Sub + Overgrow + Pinch Berry. Serperior definitely has the Speed, but the issue lies in mainly resources. Serperior just doesn't have sufficient moves on either type of attack.
Iron Tail is a move for Serperior, but when it comes down to it, it is inferior to Return...unless you want a powerful move that can cause Def drops.
Serperior learns Pursuit, but will rarely find situations to use it.
Like every other Pokemon, Serperior has access to Toxic. If you wish, replace Glare with it.
In terms of trap moves, Serperior has access to Mean Look and Wrap. Wrap is the inaccurate option, but does residual damage and is unaffected by Taunt, which is to Serperior's favour.
Swagger can work with the likes of Leech Seed, Wrap, and Glare. Flash is another one of Serperior's Status/phazing options, and works well with its fast Speed.
Twister can be considered for some Flinch power. Other than that, it can be used in a dire situation when Serperior can't afford to take another hit...
Mirror Coat can very easily obtain a KO. Serperior can take a relatively weak Fire Blast, Ice Beam, Dragon Pulse, etc. It may be difficult to fit Mirror Coat on, but it would not be to hard to force it on. To take a STAB Fire-attack, however, Occa Berry may be necessary, but it's not a bad prospect...
The issue with Frenzy Plant is that all who can learn it has access to the more flexible Leaf Storm. With Serperior, this difference is ever more profound due to Perversity. However, given Serperior's lack of moves, Frenzy Plant can be used on a Specs set (alongside Leaf Storm) in the situation where you have to have the extra 10 power, or in case Leaf Storm should run out of PP.
