I do have some suggestions, but you'll need to train a bit for this:
You do have this two already:
Chandelure
Chandelure is an amazing Pokemon. You should use it as your special sweeper. It can also learn Energy Ball which is an extra against Water/Ground type Pokemon.

Modest Nature (+SAtk, -Atk)
- Energy Ball
- Flamethrower
- Shadow Ball
- Will-o-Whisp
Scrafty
This should be your fighter. He has great defense and is also a dark type, which is a bonus.
Ability: Moxie
Adamant Nature (+Atk; -SAtk)
- Drain Punch
- Crunch
- Ice Punch
- Bulk Up
Haxorus
You don't really need a dragon type in-game, but this thing is a beast. You can also replace it with an Excadrill which is a ground type.

Adamant Nature (+Atk; -SAtk)
- Dragon Claw
- Earthquake
- Brick Break
- Dragon/Swords Dance
Sigilyph
You need a flying type to fly around the region right? Sigilyph is not just that. It is also a Psychic type so you are going to have an easy time against the many poison types in the game.

Timid Nature (+Spd, -Atk)
- Fly
- Psychic
- Roost
- Double Team