How to Train Your Flying Dragon

1. Rayquaza with Air Slash/Aerial Ace beats a Machamp raid boss in 143.4 seconds while Dragonite with Dragon Tail/Hurricane does it in 160.6 seconds. Source: https://www.pokebattler.com/raids/defenders/MACHAMP/levels/RAID_LEVEL_3/attackers/levels/30/strategies/CINEMATIC_ATTACK_WHEN_POSSIBLE/DEFENSE_RANDOM_MC?sort=TIME&weatherCondition=CLEAR&dodgeStrategy=DODGE_REACTION_TIME&aggregation=AVERAGE

Between the higher attack stat and having a flying type fast move, Rayquaza is king of the skies hands down.

2. On Defense, Dragonite's extra bulk and multi-bar charge move make him vastly better than Salamence and poor Flygon isn't even worth mentioning.

3. Against the Lati twins, Rayquaza finishes faster than anyone else, 747.6 seconds. The next best is Dragonite at 781.9 seconds. However, I intend to use one Rayquaza, two Dragonites and 3 Tyranitars in my team to save some potions and revives. The Tyranitars will deal super effective damage while lasting longer in the fight.

Source: https://www.pokebattler.com/raids/defenders/LATIOS/levels/RAID_LEVEL_5/attackers/levels/30/strategies/CINEMATIC_ATTACK_WHEN_POSSIBLE/DEFENSE_RANDOM_MC?sort=TIME&weatherCondition=CLEAR&dodgeStrategy=DODGE_REACTION_TIME&aggregation=AVERAGE

1. See above, Rayquaza wins by a crushing margin. As for whether they're good for anything else besides Machamp raids, no, at the moment or in the foreseeable future they are not.

2. Agree with above.

3. Pokebattler has our backs as above. Notably Salamence is worth using since sims place it a bit above Dragonite on average, but I would not power one up just for this reason.
Regarding Gardevoir, it will be in the pretty much exact same spot against Latis than it is against Ray, only really worth using against dragon moves in cloudy weather, where it gets better DPS than Tyranitar with almost twice the TDO of the dragon types. Granbull also becomes quite a good counter in these conditions.

tl;dr Dragons for DPS, Tyra for TDO. I'll also be using a mix of both.

Draco Meteor is complete trash on defense. Most of the time there is no Draco Meteor.

Flying is an awkward typing on offense. It is arguably the third best neutral DPS (maybe tied with psychic) after dragon and dark, however, the specialist roles that flying DPS fulfill are null.

Being only resisted by rock, electric and steel with no immunities, flying is very good for neutral DPS. However the main problem is that the SE matchups offer no chance for flying to shine.

Even dragonite can kamikaze a fellow dragon (dragons are technically the dragon specialist) and out damage ice mons that do 4x effective damage. Tyranitar will smash all psychic mons, even though it doesn't lead in DPS it is literally 7X as tanky as gengar for this matchup.

Then what exactly does flying type smash? Its effective to grass, bug and fighting, sure, but then we have Mewtwo and Moltres doing some of the most disgusting DPS in the game as well.

Only meta relevant pokemon with 4x weak to flying is heracross. We all know how common that is, and how much of a pushover it is even if you just exploit a 2x weakness.