There are multiple possible sets.
Get ready for a long answer...
Physical:
Ability: Overgrow
Item: Your choice, but Life Orb or Leftovers work
IVs: 31 atk, 0 sp. atk, 15 sp. def, 15 def, 15 HP, 31 spe
Moves:
Swords Dance
Leaf Blade
Outrage
Iron Tail
Special:
Ability: Overgrow
Item: Life Orb/Leftovers
IVs: 0 atk, 31 sp. atk, 15 sp. def, 15 def, 15 HP, 31 spe
Moves:
Calm Mind
Leaf Tornado/Giga Drain
Wring Out
Dragon Pulse
Leaf stormer:
Ability: Contrary
Item: Leftovers
IVs: 31 sp. atk, 30 atk, 30 sp. def, 31 def, 30 spe, 30/31 HP
Moves:
Leaf Storm
Hidden Power (Rock)/(Ground if HP IV is 31)
Dragon Pulse/Twister/(Grass Pledge if you are in doubles with Water/Fire Pledge on other Pokemon)
Synthesis/Toxic/Leech Seed/Leaf Tornado
Trapping set:
Ability: Either
Item: Leftovers
IVs: 31 atk, 0/31 sp. atk, 31 def, 31 sp. def, 31 HP, 20 spe
Moves:
Wrap
Toxic
Leech Seed
Synthesis/Giga Drain
Screen setter:
Ability: Either
Item: Leftovers
IV: 0/31 atk, 0/31 sp. atk, 31 def, 31 sp. def, 25 spe, 31 HP
Moves:
Light Screen
Reflect
Toxic
Energy Ball/Leaf Blade/Synthesis
The idea of each set:
Physical: Good for special walls, like Chansey or Blissey.
Special: Good for physical walls.
Leaf stormer: Rake advantage of Contrary.
Trapping set: Trap opponent with Wrap, then Leech Seed and Toxic to whittle down health. Synthesis for recovery. Synthesis over Giga Drain in case of Liquid Oozers, but it's your choice.
Screen setter: Set up Light Screen and Reflect while also inflicting poison.
My personal set
Ability: Contrary
Item: Leftovers
IVs: 30 atk, 31 sp. atk, 30 def, 30 sp. def, 30 spe, 31 HP
Moves:
Leaf Storm
Hidden Power (Rock)
Grass pledge
Twister
Phew... we're at the end. Of course, some of the sets are changeable, by swapping moves such as Leaf Tornado for Energy Ball. Hope this helped.
Note: I did make these sets, and searched up IVs to find out about hidden power. If you use the move, you can find out what hidden power it is here: https//www.smogon.com
This website also gives moves and abilities for Pokémon, as well as tiers.