Wailord @ Choice Specs
Ability: Water Veil
EVs: 248 HP / 252 SpA / 8 SpD
Modest Nature
IVs: 0 Atk
- Water Spout
- Surf
- Ice Beam
- Hidden Power [Grass]
Ferroseed @ Eviolite
Ability: Iron Barbs
EVs: 252 HP / 252 SpD / 4 Spe
Calm Nature
IVs: 0 Atk
- Rock Polish
- Leech Seed
- Substitute
- Protect
"Fast" SubSeed Ferroseed, you need to be at +4 to outspeed Wailord but at that point its just a matter of Substitute+Protect while it slowly dies (or runs out of water spout pp).
252+ SpA Choice Specs Wailord Water Spout (150 BP) vs. 252 HP / 252+ SpD Eviolite Ferroseed: 83-98 (28.4 - 33.5%) -- 0.2% chance to 3HKO
252+ SpA Choice Specs Wailord Water Spout (114 BP) vs. 252 HP / 252+ SpD Eviolite Ferroseed: 63-75 (21.5 - 25.6%) -- 1.2% chance to 4HKO
After 2 Leech Seeds it just about fails to break your sub.