Weakness Chart for Poison-type:
StenchStench: This Pokemon's attacks without a chance to flinch have a 10% chance to flinch.
Sticky HoldSticky Hold: This Pokemon cannot lose its held item due to another Pokemon's attack.
Poison TouchPoison Touch: This Pokemon's contact moves have a 30% chance of poisoning.
Here are the best movesets for Muk. Top rated Muk X/Y movesets. You can find Muk builds X/Y. Muk movesets X/Y are listed here. VGC Muk Competitive Movesets can be found here. Find various EV spreads, find the best nature for Muk in X/Y along with competitive movesets. Basic info and Movesets for evolution