Drapion: Oh my, why not take advantage of your ability, Sniper? I would suggest replacing Crunch with Night Slash, and Battle Armor with Sniper.Also, replace X-Scissor or Earthquake with Poison Jab or Cross Poison (STAB) Nature should probably be Impish, Careful, or Adamant. As for the item, Leftovers.
Zoroark: Life Orb for this little powerhouse's item, Timid nature, Your moveset is pretty nice. Although HP Grass won't help much, so go for Focus Blast. Might be a good lead instead of Drapion.
Klinklang: Probably should run Steel Gem to boost Gear Grind's power. And either Impish, Careful, Adamant, or Jolly. Also, run Clear Body as its ability. It'll help since Intimidate.
Dragonite: First off, Multiscale for its ability, PERIOD. Use Leftovers so you can recover HP. Adamant nature to boost it's attack.
Gallade: Not much to say about this guy. Life Orb for his item. Adamant for his ability.
Crobat: I love this bat, seriously. Flying Gem if you're going to run that set. And Jolly nature if you're going to run that set. Otherwise...
Nightwing (Crobat) (M) @ White Herb
Trait: Inner Focus
EVs: 4 HP / 252 Atk / 252 Spd
Jolly Nature (+Spd, -SAtk)
- Curse
- Acrobatics
- U-turn
- Cross Poison
Also, I noticed that you lack Special Attackers, and walls. Probably you should take off two more pokemon for a special attacker. Also, remember, there is going to be double and triple battles, so use moves like Heat Wave and Earthquake, alright?