Looking for a wall to replace my Aggron...and im looking at muk right now.
Sure, Weezing is better but i wanna Muk to keep it UU
heres what im thinking:

Muk@blacksludge(if i can find one...if you have any you dun need, PM me) / leftovers
Impish
Gunk shot
Acid armor
???
???

go with a curser set, which pretty much looks like a UU snorlax:

Muk@black sludge
sticky hold
impish 252hp/252spDef/6def
curse
gunk shot/poison jab
shadow sneak
brick break

while the EV spread looks like Muk will be a special sponge, it will tank both sides after getting in a few curses. curse will also boost its attack, which is a good plus. gunk shot will seriously dent anyone not resistant to it, and shadow sneak will 2HKO psychic threats including alakazam (unboosted) and azelf (after one curse). brick break, unless you're willing to get fire punch via emerald, is Muk's only option against steel types, which is a common sight in UU. besides, brick break would be superior to fire punch with aggron, probopass, and bastiodon being part rock as well.

well i say it sould be like this

ThunderBolt
ShadowBall
GunkShot
Rest/Flamethrower/Rockslide

that way you can take off more then one type of opponet

People, I present to you, the new Ghett0.

Right things wrong with that is that you have a load of special moves on a Pokemon with 65 base Spatk, when it has a highly usable 105 base Attack.

4ever_bug_catcher: You might want to consider putting Payback somewhere on there, as Curse has the wonderful effect of ensuring that Muk will be getting hit first. Pretty damn useful when you've just boosted your attack. I'd suggest putting it over Shadow Sneak.

Oddly enough I just make a Muk :O

Mine is:
Brave/Sticky hold "Likes to doze off"
252 ATK 252 DEF
Wide lens
-Curse (great buff for the slow)
-Gunk shot (lost of OHKO's with a curse added. Wide lens improves acc.)
-Shadow sneak (great against focus band and fast psychic types)
-Return, (soon to get Brick Break (taking out steel/normal types))

As for using payback, I don't endorse it because payback's main use is against psychic types, most of which will KO muk before it can use payback. Shadow sneak will at least knock off a good amount of HP to the psychic types.

I use this Muk:

@Black Sludge
Sticky Hold | Adamant
252 HP | 100 Atk | 156 SpDef

- Gunk Shot
- Curse
- Payback
- Brick Break

Payback and curse go hand in hand, and after one or two curses, you can OHKO most psychics that switch into Muk. He can take a STAB psychic attack with his good Special Defense. I run adamant for extra power, but impish or careful are just as fine. Brick Break hits steels that expect explosion on Muk.

If you want to go for a more wall-ish version, you can replace Curse with Acid Armor and use the Atk EVs for Def/SpDef instead.

Muk@black sludge/chesto berry
Adamant 252hp 252att 6 def
Curse
Poison Jab
Shadow Sneak
Rest

I don't use Muks but I believe the Substitue + Focus Punch combo would work nicely here...as would all for Slow Physical Attacking Pokemon.