I'm assuming this is in-game, And in-game, Any type combinations can work well. Altaria isn't THAT good since without it's Mega Evo. It's stats are around average and it doesn't have much going for it.
Some good things about Altaria would be-
-It can be a Mixed attacker
-It's Mega Form makes it more powerful and bulky (This doesn't really count since Scep's your Mega)
-It gets decent coverage in Fire Blast, Earthquake, Moonblast, Steel Wing and Solarbeam.
-It can take a lot of hits, Which is nice.
If you really don't want the double Dragon weakness (or a better Pokémon in general) I'll provide some replacements anyways.
Crobat: Zubat can be found pretty early on in ORAS (Granite Cave), But Crobat can be a real powerhouse with it's amazing speed and pretty good attack stats, And it can also use Fly in battle pretty well.
Pelipper: Wingull can be found really early on in ORAS, And it also evolves pretty early too (level 25). Pelipper can't make use of Fly in battle with it's horrible base 50 Attack stat, But it's a Flying type that gets Fly, And it can also take most hits decently.
Dodrio: Doduo's only found in the Safari Zone in ORAS, But Dodrio's an awesome Sweeper with it's base 110 Attack and 100 Speed. Just don't leave it in to take any attacks, It's really frail.
Skarmory: Skarmory can be found around mid-game. It's a good Pokémon with it's amazing defence and decent Attack / Special Defence. It can make use of Fly in battle while also taking a lot of non-special hits.
I only suggested Pokémon that can be found in ORAS, If you can transfer things over I might suggest some X/Y Pokémon.
I'll also suggest some more, But these ones are all other Dragons, as Altaria is commonly outclassed by other Dragons, even In-game, unless it's mega.
Salamence: Bagon's found in Meteor Falls, Althoguh it's found very late in the game(you need waterfall to get Bagon), I'd say it's worth the wait to get Salamence. Salamence is an Amazing Pokémon. It also gets Fly as soon as it evolves. It's Mega Form also makes it bulkier, And it's still awesome without Mega Evolving. It also gets good coverage with moves like Fire Blast, Thunder Fang, Earthquake, Rock Slide and Crunch.
Latios/as: The Lati twins are awesome Pokémon, Latias is the bulky one and Latios is the more offensive one. Both of these Pokémon can be used well without their mega. Both of them get good coverage with things like Ice Beam, Thunderbolt, Energy Ball, etc. This is only if you don't mind using Legendries though.
Pretty much: Altaria can work as your Fly-er even if it's your second Dragon type but it is outclassed.
If you can transfer things from XY, I'd recommend using something like Staraptor, Hawlucha, Togekiss or Dragonite.
Also if you want any movesets for these, Just ask.
