Mixed Attacking Klinklang @ Rocky Helmet
Ability: Clear Body
EVs: 252 SpAtk, 252 Atk, 4 Def
Shift Gear: A great setup move that can potentially make Klinklang a sweeper.
Substitute: Allows for a safer setup.
Gear Grind: Somewhat inaccurate, but it can get through abilities like Sturdy and compliments from Shift Gear nicely.
Thunderbolt: A nice and reliable special attack, and can help against Water types that would normally be a slight problem for pure Steel types.
My item of choice is the Rocky Helmet, because it's obvious that Klinklang resists a ton of types. Its also a Physical wall, and because most physical moves make direct contact, it'd make sense to put the Rocky helmet on.
My main strategy is substitute, set up with Shift Gear, and sweep when possible.