You can get Druddigon in the Dragonspiral Tower, which is not early. It certainly works — everything does in-game. But if you'd like a more effective Dragon type, I think you should go for Haxorus. You can get it earlier than Druddigon, it's much stronger, and it has a better movepool. I'll give movesets for both, but Haxorus is the better choice.
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Haxorus @ Muscle Band
Ability: Mold Breaker
- Dragon Dance
- Dragon Claw
- Poison Jab
- Strength / Brick Break / any other physical move
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Druddigon @ anything
Ability: Sheer Force / Rough Skin
- Dragon Claw
- Shadow Claw
- Strength
- (filler)
Hope I helped!