This is true. A Flying-type works great against both. A good Flying-type to use would be Talonflame. Talonflame is quite common, mainly due to its high Speed stat:
Talonflame (All-Out Attack)
Adamant
Ability: Flame Body/Gale Wings
252 Speed/252 Atk./4 HP
Item: Life Orb/Leftovers
Flare Blitz
Brave Bird
Protect/Taunt
Tailwind
Tailwind will ensure Talonflame has the upper hand in Speed. Flare Blitz and Brave Bird are very powerful moves, but comes with a high recoil. You can either have it hold the Life Orb for really big power, or Leftovers to compensate for some of the recoil damage. You can either run Protect or Taunt, depending on how offensive you want Talonflame to be. However, a Fire- and Flying-type has a 4x weakness to Rock, which makes Stone Edge a huge kick in the gut. Flame Body has a chance to burn the target. Burn is a good status effect because it lowers Attack. However, Gale Wings is a great ability because it puts the priority of Flying-type moves up.
A personal favorite of mine is Noivern, just because I'm a fan of Dragons. Also, it has great Special Attack and Speed:
Noivern (Special Sweep)
Modest
Ability: Frisk/Infliltrator
252 Speed/252 Sp. Atk./4 Defense
Item: Life Orb/Leftovers
Hurricane
Draco Meteor/Dragon Pulse
Roost
Flamethrower/Focus Blast/Boomburst
Roost replaces lost HP so Noivern can keep on the pain. Hurricane is a very powerful Flying-type move with lower accuracy (70%). This changes under weather conditions: 100% in Rain, 50% in Sun. Draco Meteor is a very powerful Dragon-type move, but lowers Special Attack harshly, so Dragon Pulse is a viable alternative if that is an issue. Flamethrower can cause Burns. Also, I ran Flamethrower when I used Mega Charizard Y in Double battles, where Drought takes effect when you mega evolve it. Focus Blast is a good Fighting-type attack, but at 70% accuracy. Boomburst is a move at a whopping 140 power and 100% accuracy, but as a Normal-type move, doesn't offer a lot of type coverage.
Hope this helped.
Talonflame should always use Gale Wings as its ability, as it's the sole reason why it's an OU Pokemon. Flame Body is useless in comparison:
-Swords Dance
-Flare Blitz
-Brave Bird
-Roost
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb/Sharp Beak/Sky Plate
Ability: Gale Wings
or
-Flare Blitz
-Brave Bird
-U-turn
-Tailwind/Roost
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band/Sharp Beak/Sky Plate
Ability: Gale Wings
or
-Bulk Up
-Brave Bird
-Roost
-Taunt/Will-o-Wisp
Nature: Careful
EVs: 248 HP/8 Def/252 SDef
Item: Leftovers
Ability: Gale Wings
With Modest, Noivern is now outsped by Pokemon with base 110 Speed and up with +Speed natures, like Greninja and Alakazam. It's best off as Timid as a result. Boomburst, while powerful, doesn't give Noivern any noteworthy coverage:
-Draco Meteor
-Flamethrower
-Focus Blast
-Hurricane/Switcheroo/U-turn
Nature: Timid/Naive
EVs: 252 SAtk/4 SDef/252 Spe
Item: Choice Specs
Ability: Frisk/Infiltrator
or
-Draco Meteor
-Flamethrower
-Focus Blast
-U-turn/Roost/Dragon Pulse
Nature: Naive/Timid
EVs: 252 SAtk/4 SDef/252 Spe
Item: Life Orb
Ability: Frisk/Infiltrator
An alternative is Dragonite:
-Dragon Dance
-Outrage/Dragon Claw
-Extreme Speed
-Earthquake
Nature: Adamant
EVs: 252 Atk/24 Def/232 Spe
Item: Lum Berry/Weakness Policy
Ability: Multiscale
or
-Outrage
-Extreme Speed
-Earthquake
-Fire Punch/Dragon Claw
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band
Ability: Multiscale
or
-Dragon Claw
-Extreme Speed
-Earthquake
-Roost
Nature: Adamant
EVs: 216 HP/64 Atk/228 SDef
Item: Leftovers
Ability: Multiscale