Really, any Pokemon can beat a Muk if it is a high enough level and knows the right moves. I'd suggest getting a Bronzor (in Diamond, Pearl, and Platinum) because not only will the steel subtype nullify the Poison attacks, the psychic attacks will be super effective.
But, really anything can beat a Muk, the types and subtypes just make it easier.
As for how not to fight a Muk, I could suggest not using any fighting, poison, bug, or grass attacks, as those will all be not very effective.
Muk also has a very high special defense, so using physical attacks would be advised, especially Ground type, and Psychic type attacks, like Psycho Cut, Zen Headbutt (Psychic), Dig, or Magnitude (Ground).
Those are some tips on how to beat it, but there is no sure fire way to win. Like I said, any Pokemon can beat Muk, it really just depends on how strong the Pokemon are and what it knows.
Muk is the better pokemon
A Muk Isn't A Very Special Pokemon. It Evolves From A Grimer, Which In The First Who Pokemon Games(Kanto And Johto Regions) Aren't That Hard To Find. ^.^ But, It's Hard To Find A Muk And Catch It.
you can't catch muk in emerald but you can catch grimer in the fiery path and get him to level 30 and he will evolve in to muk okay
By evolving Grimer
When your talking to the guy in front of the house there is water and the grimer and muk are in it.
A ground type Pokémon, like Groudon.
Muk is the better pokemon
A Muk Isn't A Very Special Pokemon. It Evolves From A Grimer, Which In The First Who Pokemon Games(Kanto And Johto Regions) Aren't That Hard To Find. ^.^ But, It's Hard To Find A Muk And Catch It.
Muk is #89 in the national pokedex, and it is a Poison type Pokemon.
you can't catch muk in emerald but you can catch grimer in the fiery path and get him to level 30 and he will evolve in to muk okay
grimer evoles at level 32 to muk because i have 10
By evolving Grimer
You can use some help with the Pokemon powers. Or capture the Muk forst because it's stronger. Watch out for the Mud trial!
Koga's Pokemon are: Koffing Muk Koffing Weezing
only tyranitar because he is a ground type pokemon if muk will attack than it will not work on tyranitar
When your talking to the guy in front of the house there is water and the grimer and muk are in it.
Muk, I'm not so sure about, but go to this site for help http://www.psypokes.com/dex/psydex/089/attacks