Keep in mind, this is for ubers.
Muk (M) @ Leftovers ** pup flies like
Trait: Sticky Hold
EVs: 252 HP / 106 Atk / 152 SDef
Careful Nature (+SDef, -SAtk)
- Curse
- Hidden Power [Ground]
- Sludge Bomb
- Toxic
With that said, this Muk has 414 HP, 300 Sp Def, 272 Attack. Why Toxic, you ask? Because of the omnipresent Lugia, the ultimate wall. Toxic that Lugia, Curse up on the Reflect, Sludge Bomb when you think he's going to Whirlwind you out. Hidden Power Ground is for Jirachis without Psychic or for Metagrosses.
This is GREAT in tandem with Magneton to trap that pesky Forretress (or the very very rare Skarmory).
EDIT: Forgot to mention that Muk blocks Knock Off, a very much appreciated bonus.
Again, for ubers.
Magneton @ Leftovers
Trait: Magnet Pull
EVs: 252 HP / 80 Def / 178 SAtk
Modest Nature (+SAtk, -Atk)
- Hidden Power [Ice]
- Substitute
- Thunder(bolt)
- Toxic
The reason it has so many EVs in HP and Def is for surviving a no-EVed Forretress Earthquake, just in case people still use it. The reason to use this is shown above. Toxic is for Blissey, and if the Blissey cannot break your sub in one hit, keep Substituting until it's forced to switch or Aromatherapy.