Mandibuzz is completely viable in OU atm considering it has access to Defog, Toxic, and can even U-Turn out on a targets. Personally I like using a Mandibuzz consistent of Defog, Roost, Foul Play, and U-Turn because threats like Mega Diancie, Rotom-W, Thundurus, and Raikou are a persistent pain to deal with. It's a good wall but remember special attacks are going to give Mandibuzz problems.
As far as VGC goes, Mandibuzz is a good call since it can provide STAB Foul Play and Tailwind support. Snarl is good support option but again my main concern are "super effective" special attackers like Rotom-W, Sylveon, and Thundurus/Zapdos will give Mandibuzz issues. On the plus side, Mandibuzz has a base 80 speed which can help it get off Snarl support against unsuspecting special attackers and give your side an artificial layer of special bulk. Overcoat is an amazing ability which prevents Mandibuzz from getting spored or even Rage Powder as well as gives Manduzz immunity to sand and hail damage. Most support Pokemon will likely get spored on but Mandibuzz can easily avoid these issues and either Tailwind or Foul Play its target immediately.
As far as VGC goes, Mandibuzz is a good call since it can provide STAB Foul Play and Tailwind support. Snarl is good support option but again my main concern are "super effective" special attackers like Rotom-W, Sylveon, and Thundurus/Zapdos will give Mandibuzz issues. On the plus side, Mandibuzz has a base 80 speed which can help it get off Snarl support against unsuspecting special attackers and give your side an artificial layer of special bulk. Overcoat is an amazing ability which prevents Mandibuzz from getting spored or even Rage Powder as well as gives Manduzz immunity to sand and hail damage. Most support Pokemon will likely get spored on but Mandibuzz can easily avoid these issues and either Tailwind or Foul Play its target immediately.
