PKMN White team help?

Let's break this down individually:

Crobat: For the most part, your Crobat is okay. You can go defensive and break some Stalling Pokemon, or offensive with Life Orb/Choice Band. You'll typically want a Jolly nature, although Adamant can work if you want some extra power. Remove Poison Barb as it's only helping one move - Poison Fang, and that move can go in lieu of Cross Poison. Confuse Ray is debatable. Roost is a nice option for healing, and it also removes your Flying weaknesses for one turn. Taunt is almost mandatory on something as fast as Crobat, stopping things from setting up either entry hazards or boosting stats. U-turn can work to scout some things, and Pursuit is always nice for catching frail Psychics and Ghosts that try to flee.

Breloom: looking pretty good here. Breloom gets the amazing ability of Technician through the Dream World(though I'm not sure it's released yet. You can still use it on Online Servers, though). Running Spore, which will either force a switch or they'll try to stay in and wake up, Swords Dance is an EXCELLENT addition, as you can boost on the switch or just dance in their face, taking your Attack to insane levels. Mach Punch is good STAB priority, and helps Breloom's less-than-stellar speed. Facade can also work with ToxicHeal, as its power is doubled to 140 since your poisoned. Should you go defensive: Protect, Substitute, and Leech Seed are very, very nice options. A Jolly or Adamant nature works best with this guy, and he can also run Life Orb, Choice Band/Scarf.

Ferrothorn: You seem to have taken an offensive route with him. This guy has a ton of moves to pick from. You'll really want Leftovers on him, unless you feel like going offensive all the way and using Choice Band. Defensively, use Relaxed; offensively - Brave. Ferro's speed isn't going to help him much, so you might as well just ignore it. Ferro is amazing at setting up Spikes and/or Stealth Rock, and entry hazards are your best friend. He can also run Leech Seed and Protect, which, combined with Leftovers, is a very nice form of recovery. Thunder Wave is good for crippling faster opponents, and should you choose not to, Gyro Ball takes advantage of your low speed as well as STAB. A set something like this:
Ferrothorn@Choice Band
Brave
Iron Barbs
248 HP, 252 Atk, 8 SpD
-Gyro Ball
-Power Whip
-Explosion
-Not really sure

or if you want more defensive and tank-ish:

Ferrothorn@Leftovers
Relaxed
Iron Barbs
252 HP, 88 Def, 168 SDef
-Spikes/Stealth Rock(you can run both, just replace something else)
-Leech Seed/Protect/Thunder Wave(you can run more than one)
-Gyro Ball/Power Whip(if running both, replace the last slot)
-Stealth Rock/Protect/Thunder Wave/Leech Seed

Gallade: gets Close Combat - use it. Coming off of his high attack, as well as getting a STAB boost, it's powerful. He gets priority in the form of Shadow Sneak, can Taunt, and boost up in either Swords Dance or Bulk Up. SD offers immediate power, while Bulk Up can give you good defense and abuse the hell out of Drain Punch. With his average-ish speed, Gallade can abuse a Choice Scarf, using Zen Headbutt for flinch. Adamant/Jolly is typically good, though Careful abuses his naturally good Special Defense if you use Bulk Up. Additionally, he gets Ice Punch and Stone Edge- very good to help score some hits against Dragons/Gliscor or Flying-types. Leftovers helps on Bulk Up, Life Orb is good offensively while allowing choice of your moves- also works well with Drain Punch.

Gastrodon: LEFTOVERS. Gastrodon can be a special tank, and boy, is it awesome. Toxic is great for stalling the hell out of things, while you sit back and Protect/Recover until they die. If you can catch a Storm Drain boost, you can also Choice Specs and hit back with a vengeance. Something like this, perhaps?:

Gastrodon@Leftovers
Sassy/Calm(less speed, or weaken attack you're not even using, unless you run Earthquake over Earth Power)
Storm Drain
252 HP, 4 SAtk, 252 SDef
-Recover
-Ice Beam/Toxic
-Scald
-Earth Power/Earthquake(protect can be thrown in somewhere if you want it)
~This is pretty Special Defensive, and Gastrodon can do it. If you go full Special Attack, just switch the SpDef and SpAtk EVs, and maybe shift a small handful of HP into SpDef.

Salamence: 'Mence doesn't commonly go all-Special in Gen V - usually it's Dragon Dancing or Mixing. Speaking of which...Moxie. An awesome ability, it also works super well with Dragon Dance. Air Cutter isn't really that useful, swap it out with something like Draco Meteor, which will put a huge dent in most things. Choice Specs gives you even more power, but you'll be restricted to one move. 'Mence can run a bunch of sets, and a bunch of items.

Overall, your team is mostly built right. I only put sets up for the 'mons whose EVs looked kinda funky to me. KoL will probably have more and better advice, though. So I'd wait for him to say anything before going around and changing anything.

 

Roost makes it land, so ground moves are now able to hit it for the turn, but Rock, Ice, and Electric moves are no longer Super Effective for that turn.

 

Shell Bell has nothing on Leftovers. Acrobatics is a good move because its power doubles if you don't have a hold item. With a Flying-type Pokemon and a Flying Gem, that's a lot of power. I believe it goes from base 55 to 110 using Flying Gem, doubling to 220 since you're no longer holding an item, then to 330 with STAB. That's 660 Super-Effective, and 4x Super Effective is just ridiculously powerful(my math right be wrong, though. I always get confused on the order in which this stuff takes place. Still insanely strong). Brave Bird only has about half to three-quarters of that power, and you have recoil to boot. Acrobatics stays strong at about 165 factoring in STAB(again, might be wrong on the math), while Brave Bird is 180 with recoil. Acrobatics stays strong and helps promote longevity.

 

tbh i'm the serious offence type so i will try to help by telling you the best pokemon moves for the pokemon. it may not be the best advice and may sound dumb to other pro's like KoL but this is me not him, ok?
Crobat: Air Slash/Sludge Bomb/Giga Drain/X-Scissor
Breeloom: Sky Uppercut/Stone Edge/Drain Punch/Focus Blast
Ferrothorn: Power Whip/Stealth Rock/Thunderbolt/Explosion?
Gallade: Leaf Blade/Night Slash/Psychic/Earthquake
Gastrodon: Muddy Water/Ice Beam/Rock Slide/Sludge Bomb
Salamence: Draco Meteor/Flamethrower/Aerial Ace/Dragon Pulse or Brick Break
P.S i focus on attack and have a wide range of different types of attacks to find at least one super effective move on basically any pokemon you face and i don't worry about raising stats just defeating them as quickly as i can. hope this helps ~~