Well, the very first time you fight them, their Pokemon are around 49-55. The all start with 5 Pokemon, excluding the Champion, who has 6. Victory Road is always a good option for training, so is Mt. Cornet. I would get them to at least 57 or above.
Infernape- I would keep flamethrower, but not fire blast. Mach punch isn't bad, But I like Thunder Punch for it's water and flying weakness. Close combat is not bad at all, other than the stat drop. Maybe replace Fire blast with shadow claw. (for psychics)
Garchomp- Earthquake is an amazing move, dig is basically an evasive move of the same type, but not as powerful. Give him a fire or rock move (such as stone edge) to fight his 4x Ice weakness. Dragon claw is very good, and crunch is okay, and helpful for fighting Lucian.
Magnezone- Again, get rid of thunder, thunderbolt is more reliable. Flash cannon is good, but if you have that, you don't really need magnet bomb. Magnet rise will help prevent ground moves, (4x weakness) For your last move, you could have tri-attack, substitute, or a good hidden power if you have one.
Crobat- I personally love sludge bomb, and shadow ball is great for fending off psychics. Fly, I would keep. And crunch, I would choose between that or confuse ray.
Golduck- Surf is great, but maybe try to get ice beam instead of blizzard. Zen headbutt, I don't see anything wrong with that, and for your last move, maybe dig.
Haunter- This guy is great, but even better if you could trade it over to a different game and get it back. (evolving into Gengar) Shadow ball is amazing for him. Dark pulse isn't bad, but I would really get focus blast for dark types. (...which sadly can only be achieved with Gengar.) If you can't evolve him, I guess your set's okay.
By the way, send out infernape for the first elite. he does well against bug types.
Hope I could help. :)