There are multiple possible sets.
Get ready for a long answer...
Item: Your choice, but Life Orb or Leftovers work
IVs: 31 atk, 0 sp. atk, 15 sp. def, 15 def, 15 HP, 31 spe
Item: Life Orb/Leftovers
IVs: 0 atk, 31 sp. atk, 15 sp. def, 15 def, 15 HP, 31 spe
Leaf Tornado/Giga Drain
IVs: 31 sp. atk, 30 atk, 30 sp. def, 31 def, 30 spe, 30/31 HP
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
IVs: 31 atk, 0/31 sp. atk, 31 def, 31 sp. def, 31 HP, 20 spe
IV: 0/31 atk, 0/31 sp. atk, 31 def, 31 sp. def, 25 spe, 31 HP
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
IVs: 30 atk, 31 sp. atk, 30 def, 30 sp. def, 30 spe, 31 HP
Hidden Power (Rock)
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.