Choice Scarf
Jolly
Outrage
Earthquake
U-turn
Stone Edge / Fire Blast
4 HP / 252 Atk / 252 Spe
Flygon's good Speed stat and excellent type coverage makes it a workable Choice Scarf user in OU. It is able to revenge kill many threats, such as Dragon Dance Dragonite and Haxorus, and Choice Scarf Hydreigon; it also can Speed tie with +1 Volcarona or Salamence at the very worst. It still takes hardly anything from entry hazards, is immune to Thunder Wave, and can use U-turn to keep momentum. What sets Flygon apart from Landorus, the other Ground-type Choice Scarfer with U-turn, is its access to STAB Outrage. With its excellent pair of STABs, Flygon is possibly one of the most efficient late-game cleaners in the game due to the number of Pokemon it can hit. It tends to force the opponent into hanging onto their more defensive Pokemon and lose offensive momentum. As such, Choice Scarf Flygon is useful in all stages of the match, as it can keep offensive momentum in the early-game with U-turn, revenge kill threats mid-game, and clean up late-game.
Outrage and Earthquake are obviously Flygon's two excellent STAB attacks. U-turn allows Flygon to maintain momentum for the team and force switches to rack up entry hazard damage. Stone Edge is preferred in the last moveslot, as it allows Flygon to revenge kill Volcarona. However, if the fiery moth of no concern, Fire Blast can be used to give Skarmory a nasty surprise upon switch-in.