From an RMT I did:
Cradily @ Leftovers ~ Careful
Ability: Suction Cups
EVs: 252 HP / 4 Atk / 252 Def
- Curse
- Rock Slide
- Seed Bomb / Earthquake
- Recover / Rest
One of the most annoying Pokemon in existence with a really annoying set. Curse Cradily is a complete pain to take down once it gets set up, especially with Sandstorm adding to its already great Sp. Def. Rock Slide is standard because flinch is handy, and it's also more helpful STAB than Seed Bomb. If you really must have Grass coverage you can run Seed Bomb as the second attacking move; otherwise go with Earthquake, which will let you hit anything except Torterra, Flygon, and Levitate Bronzong (and it's not like Seed Bomb would help against those guys). Recover is preferred over Rest due to more reliable recovery, but Rest can be used if you're afraid of Toxic. Put EVs into HP and Def; Cradily's Sp.Def is good enough that you can just run Careful and it'll be fine. Ideally this will be in Sandstorm anyway, so lower SpD doesn't really matter.
Is inevitably done in by a critical hit.