In my opinion, this is the best Probopass set. In fact, all Probopass I see these days are some variant of this set.
[SET]
name: Offensive
move 1: Stealth Rock
move 2: Volt Switch
move 3: Earth Power
move 4: Power Gem / Flash Cannon
item: Air Balloon / Leftovers
ability: Magnet Pull / Sturdy
nature: Modest
evs: 160 HP / 252 SpA / 96 Spe
[SET COMMENTS]
<p>While an offensive set may seem weird on a Pokemon with a base 75 Special Attack stat, this set makes Probopass a competent attacker. Offensive teams need a pivot or two, and Probopass is an excellent one. Probopass has a good set of resistances, allowing it to easily switch in on a multitude of offensive threats, such as Cinccino, set up Stealth Rock, and safely switch in a powerful sweeper with Volt Switch. As for the other moves, Earth Power hits a lot of common Pokemon hard such as Emboar and opposing Probopass. Power Gem has better coverage, although Flash Cannon is also usable, as it is Probopass's most powerful STAB. When running Magnet Pull, Probopass also has the niche of trapping Steel-types. While there aren't that many Steel-types in NU, being able to trap Klang, Lairon, Mawile, and opposing Probopass is useful.</p>
[ADDITIONAL COMMENTS]
<p>Max Special Attack EVs and a Modest nature are used to maximize Probopass's offensive prowess. 96 Speed EVs are used for outspeeding unboosted Shell Smash Torkoal, as well as minimum Speed Regirock and standard Golem, while the rest of the EVs are dumped into HP. If you don't need Stealth Rock, it can be replaced with an attacking move or Thunder Wave. Rocky Helmet is an interesting item choice because Probopass can switch in on a lot of physical contact moves, but Air Balloon and Leftovers are usually more useful.</p>
<p>Magnet Pull should be used if Steel-types are particularly troubling to your team. Sturdy allows Probopass to survive a powerful attack that would otherwise knock it out, provided it has full HP. The item choice should reflect the ability choice: Air Balloon is better with Magnet Pull because it allows you to trap other Earth Power Probopass, and gives you an immunity to the very common Ground-type moves; Leftovers goes better with Sturdy because with it Stealth Rock won't break Sturdy anymore.</p>
<p>Probopass is a fantastic teammate for a lot of offensive threats. Swoobat can set up on, and force out, the Fighting- and Ground-types that threaten Probopass. Probopass helps Swoobat by beating Cinccino, setting up Stealth Rock, and providing a safe switch in with Volt Switch. Articuno beats most of Probopass's checks pretty easily, while Probopass can trap the Steel-types that counter Hidden Power Ground-less Articuno. Dragon- and Flying-types, such as Dragon Dance Shelgon and Swellow, also appreciate Probopass's ability to get rid of Steel-types. For defensive partners, Misdreavus prevents Pokemon from spinning away Probopass's hazards, and is immune to both the Ground- and Fighting-type attacks that Probopass is 4x weak to. Musharna, while lacking an immunity to Ground—and only being resistant to—Fighting-type attacks, still has the bulk to set up on them, even when backed with STAB.</p>
[SET]
name: Offensive
move 1: Stealth Rock
move 2: Volt Switch
move 3: Earth Power
move 4: Power Gem / Flash Cannon
item: Air Balloon / Leftovers
ability: Magnet Pull / Sturdy
nature: Modest
evs: 160 HP / 252 SpA / 96 Spe
[SET COMMENTS]
<p>While an offensive set may seem weird on a Pokemon with a base 75 Special Attack stat, this set makes Probopass a competent attacker. Offensive teams need a pivot or two, and Probopass is an excellent one. Probopass has a good set of resistances, allowing it to easily switch in on a multitude of offensive threats, such as Cinccino, set up Stealth Rock, and safely switch in a powerful sweeper with Volt Switch. As for the other moves, Earth Power hits a lot of common Pokemon hard such as Emboar and opposing Probopass. Power Gem has better coverage, although Flash Cannon is also usable, as it is Probopass's most powerful STAB. When running Magnet Pull, Probopass also has the niche of trapping Steel-types. While there aren't that many Steel-types in NU, being able to trap Klang, Lairon, Mawile, and opposing Probopass is useful.</p>
[ADDITIONAL COMMENTS]
<p>Max Special Attack EVs and a Modest nature are used to maximize Probopass's offensive prowess. 96 Speed EVs are used for outspeeding unboosted Shell Smash Torkoal, as well as minimum Speed Regirock and standard Golem, while the rest of the EVs are dumped into HP. If you don't need Stealth Rock, it can be replaced with an attacking move or Thunder Wave. Rocky Helmet is an interesting item choice because Probopass can switch in on a lot of physical contact moves, but Air Balloon and Leftovers are usually more useful.</p>
<p>Magnet Pull should be used if Steel-types are particularly troubling to your team. Sturdy allows Probopass to survive a powerful attack that would otherwise knock it out, provided it has full HP. The item choice should reflect the ability choice: Air Balloon is better with Magnet Pull because it allows you to trap other Earth Power Probopass, and gives you an immunity to the very common Ground-type moves; Leftovers goes better with Sturdy because with it Stealth Rock won't break Sturdy anymore.</p>
<p>Probopass is a fantastic teammate for a lot of offensive threats. Swoobat can set up on, and force out, the Fighting- and Ground-types that threaten Probopass. Probopass helps Swoobat by beating Cinccino, setting up Stealth Rock, and providing a safe switch in with Volt Switch. Articuno beats most of Probopass's checks pretty easily, while Probopass can trap the Steel-types that counter Hidden Power Ground-less Articuno. Dragon- and Flying-types, such as Dragon Dance Shelgon and Swellow, also appreciate Probopass's ability to get rid of Steel-types. For defensive partners, Misdreavus prevents Pokemon from spinning away Probopass's hazards, and is immune to both the Ground- and Fighting-type attacks that Probopass is 4x weak to. Musharna, while lacking an immunity to Ground—and only being resistant to—Fighting-type attacks, still has the bulk to set up on them, even when backed with STAB.</p>