So, what are Flying-types, really?
The Purpose of the Flying Type:
The original purpose of Flying-type was to have a means of an avian enemy that would be immune to Ground-type attacks, and to have non-elemental filler type. The other two, actually three counting Bug but Bug is a special case, Normal and Dragon, were too weak and too strong respectively. Flying also served as a balancing factor for the type chart, as a nerfer for the primary types and Bug, and as a means of defeating Fighting-type. The former was because of the Legendary Birds, which needed a quad weakness to take them down(and Electric needed more than one weakness), and the latter was because Psychic was purposely designed to be broken, and Fighting itself was meant to representative of physical offense in JRPGs(Warriors and Monks etc.)
The original purpose of Flying was expanded upon when Flying was granted to be representative of the traditional JRPG element of Wind. With this addition, Flying went from a non-elemental type to something of a true elemental type in-training. Nonetheless, Flying's original role, and its earlier role as the Bird-type still looms large for the type, which makes it open for a true Wind-type to fill in the open role.
The Aesthetic Archetypes of Flying Types:
The Flying-type has rarely been a primary type, as such it never got a true associated color. But the type itself is generally shown in a bluish color, with Tornadus being green to represent the wind. Aesthetically, Flying can be divided into following categories:
Anything with wings and can fly, basically. It separates into Winged Insect, Winged Lizard(which contains pterosaurs, early birds and dragons), Bird, and Winged Mammal. So far there hasn't been a winged machine to fill in role, though there is one Winged Fish in the form of Mantyke-line.
Species that do not fly, but rather glide with wind. Nonetheless, they are shown as if they are flying. Generally non-bird Pokémon are in this category
This consists of species that would normally would get Levitate, but because they want to have other abilities, are put into Flying-type instead.
The In-game Archetypes of Flying Types:
Flying-types can be categorized in the following groups:
Primary Early Flying-type: The first Flying-type you encounter in the dex. It is a fairly traditional archetype. Three stagers are generally in 479-499 range, and second stagers are around 450-460 range.
Secondary Early Flying-type: Same as above, but the secondary one you encounter. Unlike the primary ones, there are no three-stagers for this group, so they only have two stagers, and Oricorio.
Mid-game Flying-type: The "upgrade" to the early Flying, this is the Flying-type you should get after evolving your primary Flying-type, but most people won't. They are generally two staged and around 470-500 range.
Late-game Flying-type: The late game version of the above, these are generally two staged and around 490-510 range.
Gimmick: Generally occuring mid-game and has no evolution, the gimmick is a generally weak Flying-type that represents some gimmick like a special Move or Ability.
Though there are other archetypes Flying are associated with like Early Bugs, they are archetypes of Bug-type Pokémon, not Flying-type Pokémon.
The Stat Archetypes for Flying Types:
The Balanced: A balanced Pokémon with no speciality outside of Speed, these are generally utility Pokémon that are meant for in-game use.
The Attacker: Poor-man's version of the sweeper, Flying-type offensive Pokémon tend to have okayish defenses, good Speed and decent offense.
The Speed Tank: A variation of the tank, Flying-type Bulky Offense Pokémon tend to have good speed and some means of buffing their speed, and okay offenses. They generally oriented in one offense or defense.
The Speed Stallbreaker: A variation of the dual offensive, these are generally Pokémon with good offenses, mediocre speed, decent HP and bad defenses.
The Defensive: Species with good defense in one area and slightly below average in other, these are Flying-type's variation of the wall. They don't have much HP.
The Annoyer: Generally existing for Speed and status spam, annoyers are slightly below average Pokémon that spam status moves.
Flying-types are generally fast balanced Pokémon with very few species with stats above 120.