Cheauking's fantastic Poison/Dark combo leaves its only weakness to Ground. Its massive 130 Defense and 75 HP alongside Intimidate make it a great physical tank, although its 80 Special Defense is still quite usable, especially if its a Special Defensive built. Its offenses of 105/100 is good enough to not make it super passive in a battle. Access to Leech Seed to sap opponent's HP every turn is a nice niche over Pain Split.
Its only weakness is its 60 Speed, meaning that you're mostly going to have to take a hit first. Also, in Procyon and Deneb, Weezing has access to Eviolite, boosting its both of its Defenses a lot and providing a resistance to Fairy in exchange for a weakness to Psychic instead of Ground due to Levitate. However, Cheauking does have its own perks, such as Intimidate, higher Attack stats, and Dark typing to tank Dark and Ghost moves.
Overall, Cheauking is a very strong Physical Wall and Special Wall in one package with good offensive presence with Sludge Wave and Dark Resolve.