Bombirdier

Bombirdier is.... okay. It's got an outstanding Flying Type moveset, but it lacks the power to really utilize it. Still, it can make a decent second or third string Flying attacker... but it's not really worth investing in.

Best PvE Offensive Moveset

• Wing Attack and Fly is an amazing Flying Type moveset, arguably the best non-signature moveset that Bombirdier could have ever hoped for.
• Rock Throw, Aerial Ace, and Payback are sub-par.

Best PvE Defensive Moveset

• Rock Throw is the defensive Fast Move of choice thanks to its higher power and off-type advantage. 
• Aerial Ace is the top Charged Move for Bombirdier on defense, though Fly's higher power makes it worthwhile as well.
• Wing Attack doesn't work as well on defense, as it shares type with Bombirdier's best Charged Moves.
• Payback is nice, but its energy cost is far too high.

Wing Attack benefits from STAB and has a much higher energy generation than Rock Throw. Rock Throw can be used in very specific formats, such as the Flying cup, but it is otherwise a bad move.

Fly has excellent DPE and a moderately low cost, and is a great choice as Bombirdier's main attack. However, as Bombirdier is rather glassy, Aerial Ace's lower cost may actually be preferable sometimes. Payback benefits from Bombirdier's other STAB and provides coverage against Steel-type Pokemon.

Running a full Flying moveset (Wing Attack + Fly AND Aerial Ace) is a viable option as well