If every Dragon type decides to battle, which Pokémon would come out on top?

Mega Altaria for me. Weaknesses are Poison, Steel, Ice and Fairy or 4 attacks most Dragon Types do not possess and is immune to Dragon type attacks while having STAB Dragon, FAIRY and access to Ice Beam. Granted they did nerf my Mega by removing Return(hence no more 102 power Normal → Fairy(via Pixelate), hence much stronger via STAB) so I'd have to resort to Hyper Voice instead. Good bulk with Roost to recover too. Only one that might give it trouble is Archaludon from its STAB Steel(which is something that Altaria can't really cover that well).

Yeah Fire/Dragon is really overlooked but it'd get destroyed by the likes of Flygon or Garchomp given its Ground weakness. Also forgot my Altaria is weak to Ice but virtually no Dragon has Ice moves to begin with(Poison and Steel though is another story). Good pick on Turtonator though as its one of my favorite Dragon types.

Wait, Mega Feraligatr is Dragon type?!

NO NOT MY TATSUGIRI'S WORST ENEMY!!!