Fire

Flying Attacks

Ghost

Flying attacks are most effective against Grass, Fighting, and Bug Pokémon. (Another quad-weakness for Parasect.)

Flying attacks are weakest against Electric and Rock Pokémon.

In general, Flying attacks are pretty mediocre. Since there are no pure Flying species, your Pokémon will most likely have access to more damaging attacks.

Flying attacks can't be completely written off, however. They are very useful for fighting Ghost Pokémon. Since defense against Flying attacks is based on the Defense statistic and the Gastly series have considerably lower Defense scores than Special scores, Flying attacks are an effective way to get past both their immunity to Normal and Fighting Attacks and their high Specials.

Mirror Move is an interesting oddity. Since it copies the last attack your opponent used against your Pokémon, whatever type that attack might be, it's not really comparable to the other Flying attacks. It certainly has novelty value and can prove useful in certain circumstances.

Consider, however, that when using a Mirrored attack, the effect is just as if the Pokémon knew the attack and used it itself, both with regards to the victim's vulnerability and the attacker's 50% type-matching damage bonus (or lack thereof). Thus it is likely that a Mirrored attack will not be as effective as another Flying attack, particularly if the victim is using attacks that take advantage of its own type(s), to which it will probably have some resistance.

This is a tough one. While Drill Peck is both more powerful and slightly more accurate than Fly, Fly has alternate uses both in and out of battle.

Fly is indispensable when playing the game, to quickly get from place to place. And inside of battle, it makes your Pokémon virtually invulnerable for one turn (excepting Swift), thus draining the PP of the victim and prolonging the effects of burns or poisonings (on both Pokémon).

On the other hand, it telegraphs your attack, so your opponent might get the chance to switch out his Gengar before you unleash on him. Also note that, as with all HMs, once a Pokémon has learned Fly, it will be stuck with it forever (barring use of a cheating device).

If Drill Peck is available to your Flying Pokémon, and you are more concerned with battling than game play, Drill Peck probably has a slight edge due its reliability and damage. But the edge is very slight and Fly is still a solid (and useful) attack. The "better" attack is clearly just a matter of preference.

No contest. Peck has a lot of PP, but not enough to overcome its unbearable weakness. Drill Peck is far superior.

At first glance, Sky Attack looks like a really good attack. It's very accurate for a high-powered attack, but it takes two turns to attack, which essentially cuts its power in half. (Fly's Average Damage is not affected in the above chart, because your Pokémon is not a sitting duck during the first turn.)

Even worse, your Pokémon spends one turn charging before attacking (as opposed to the one turn of recovery that follows a Hyper Beam), during which time he is vulnerable to both direct attack (unlike Fly) and a possible switch-out of Pokémon weak to Flying attacks. And because the delay is on the first turn, it's not even valuable as a "finisher" like Hyper Beam. That is, there is no chance of taking out your opponent on the first turn, so you might as well attack twice with a single-turn attack. There's a chance the victim will be defeated on the first turn and you'll actually do more damage in two turns with Drill Peck (or Fly). (With Hyper Beam, there is a chance of knocking out the opponent before your Pokémon has to recharge, thus sparing it from another enemy attack.)

The net result is that Sky Attack is actually less powerful, less accurate, and has significantly fewer PP than both Drill Peck and Fly.

Wing Attack is very accurate and has a lot of PP, but, like Peck, is so miserably weak that it's not even worth considering. Drill Peck (or Fly) is clearly a better choice.

For some half-Flying Pokémon, Wing Attack the only available Flying attack. Even for these Pokémon, however, Wing Attack is probably not a very good idea.

None.