Bisharp @ Leftovers
Trait: Defiant
4 HP / 252 Atk / 252 Spe
Adamant/Jolly Nature
~ Substitute
~ Rock Polish
~ Sucker Punch/Night Slash
~ Low Kick/Brick Break

Substitute - Rock Polish - Sweep. Night Slash is most of the time preferred over Sucker Punch, because you'll already outspeed a lot and Sucker Punch is pretty unreliable, and has less PP. If you fear screens, or want to hit Porygon2 harder, Brick Break is an option, but Low Kick is generally preferred because there are a lot more heavy pokémon that get hit harder.