Ok, before I post, stop giving it Sludge Bomb over Sludge Wave.
This is my set, both in-game and on PO.
Coverage Wall
[Goodra] (F) @ [Assault Vest] Trait: [Gooey] EVs: [4 HP / 252 SAtk / 252 SDef] [Calm] Nature (+SDef, -Atk) - Dragon Pulse - Focus Blast
- Flamethrower
- Ice Beam
This set has worked wonders for me, as it can get an SE hit on 90% of the metagame.
Dragon Pulse is the basic STAB. Focus Blast is for TTar/Heatran/etc,
Flamethrower ruins Forretress/Ferrothorn/Scizor
Ice Beam takes out Gliscor, and other things with x4 Ice Weaknesses.
This thing has insanely high special defense, it can take anything. The only special attacker you should ever switch it out against is a Togekiss, because it has Roost, and even though Dazzling Gleam will only do 15% or so, it can't win a stall war. True, it could run Sludge Wave instead, but when I tested that, this set made it better overall.
Gooey ruins any physical attacks that might want to take it out, especially Khangaskhan, which gets a -2 speed boost from any attack. Using Power-up punch or fake out will give it a -2 speed boost, allowing Goodra to focus blast it, then focus blast it next turn to KO. And it has enough HP that Power-up punch won't KO it.