Salamence

Salamence had its place as the best Dragon Type in the game for a time, but that time has passed. That's not to say that Salamence is bad, just not as strong as it once was. If you have a good Bagon, then it might be worth raising a Salamence for your Dragon Team, even now.

Best PvE Offensive Moveset

• Dragon Tail is the fast move of choice.
• Outrage is a reliable and strong move, meaning it will generally be the superior option. Draco Meteor is actually stronger on paper, but if Salamence drops with more than 50 energy stored, it's generally weaker in practice.
• Fire Fang and Fly have some synergy, mainly against Grass Types, and deal a lot of damage together despite a lack of STAB on the former.
• Bite and Brutal Swing makes Salamence a surprisingly good Dark Type attacker.
• Fire Fang and Fire Blast can work for Fire damage, but aren't great.
• Hydro Pump and Crunch have no genuine utility on Shadow Salamence.

Best PvE Defensive Moveset

• Dragon Tail excels in STAB power, but Fire Fang shines against many of Salamence's counters.
• Bite offers no defensive utility on Shadow Salamence. 
• Brutal Swing is generally the best option here due to its wide neutral coverage and the fact that it's 3-bar. On defense, Crunch is basically a copy of Brutal Swing, but easier to dodge.
• Outrage is a great choice to squeeze in damage, while Fly is a bit weaker.
• 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. Return has no real use.