To answer your questions, here is a reccomended set on probopass from smogon:
[SET]
name: The Set
move 1: Earth Power
move 2: Hidden Power Ice / Flash Cannon
move 3: Thunder
move 4: Explosion / Magnet Rise
item: Leftovers / Choice Specs
ability: Magnet Pull
nature: Modest / Quiet
evs: 252HP / 174SPATK / 84SPD
[SET COMMENTS]
<p>One of the worst Pokemon in Advance got a much-needed evo, and the result is... less than exciting, but at least it's workable. Magnet Pull is still available to base a set around, so here it is - the given EVs outspeed minimum Aggron in UU and Mawile in NU, so feel free to come in and mess them up with Earth Power (watch out for Focus Punch.) If you don't care about that, just pump special attack and use Quiet - Explosion will be stronger. Hidden Power Ice provides some nice coverage, and Thunder beats down Water types while giving some paralysis support. You're welcome to try Magnet Rise if that floats your boat, but Explosion may end up being all Probopass can do.</p>
<p>If you want a Choice Specs set, nothing really changes here, though obviously you won't use Magnet Rise.</p>