Shadow Salamence

Shadow Salamence is an insanely powerful dragon, able to dish out more damage than the vast majority of its competition. It's an expensive investment, but its performance is definitely worth the high stardust cost and even an Elite TM to unlock Outrage.

Best PvE Offensive Moveset

• Dragon Tail can be paired with Outrage for maximum damage potential.  
• Draco Meteor is an okay alternative for Dragon-type DPS.
• Fire Fang and Fly can definitely work to maim Grass Types, a job that Shadow Salamence is surprisingly good at.
• Bite pales in comparison to Dragon Tail.
• Hydro Pump is preferred to Fire Blast for being faster and stronger. 

Best PvE Defensive Moveset

• Dragon Tail excels in STAB power, but Fire Fang shines against many Salamence counters.

• Bite offers no defensive utility on Salamence. 

• Outrage is Salamence's only multi-bar charge move, making it a great choice to squeeze in damage.

• Hydro Pump is a decent charge move because of how early it hits.

• Although Draco Meteor hits late, it does a number if not dodged.

• Fire Blast’s counter coverage is offset by a late damage window.

Dragon Tail provides average damage and decent energy generation that Salamence needs for its expensive moves, as well as solid neutral coverage. 

Fly is Salamence's cheapest Charged Attack and benefits from STAB; its excellent overall parameters allow it to become Salamence's primary weapon. Outrage is fairly expensive, but it deals tremendous damage and is cheaper than Salamence's other options. Fire Blast can be ran instead to incinerate Steel-type Pokemon that would otherwise wall it, but its extreme cost makes it an unreliable move. Draco Meteor is an alternative option to Outrage for more even power, but its drawback and slightly higher cost makes it a generally inferior option. Hydro Pump can be used for coverage, but Fire Blast is generally better for that purpose. Frustration obviously has no use.