Roaring Moon is a poor choice for a playthrough because it's obtained in Area Zero, just a few battles before the end of the game. Better Dark types include Lokix and Weavile; Haxorus and Garchomp are excellent if you need a Dragon type. This late availability matters considerably less in the DLCs, particularly The Indigo Disk. Though Roaring Moon doesn't have a great matchup into the Blueberry Elite Four, it can put in some work against Drayton and Kieran.
If you must use Roaring Moon, here's a set:
Roaring Moon
Ability: Protosynthesis
- Dragon Dance (Level 56)
- Crunch (TM108)
- Dragon Claw (TM78)
- (filler)