You're new to this, I know...but it takes a lot of practice to actually realize what you need on one of these.
I'll try to give a step by step analysis.
Sawk
Giga Impact
Retaliate
Reversal
Close Combat
Item: Fist Plate
First off, as with all Pokemon, make SURE you use Protect unless something isn't allowing it to be efficient. Secondly, Sawk is a good Pokemon, but there are actually better alternatives for what he does...I.E. Conkeldurr, Terrakion, Scrafty.
The item also isn't necessary, this will also go for all 6 Pokemon. Plates are rarely to never used. Go with a gem of the STAB move if anything- 50% boost on one attack usually 1HKO's anything that it's normal against. If you think the Pokemon is great and just needs a speed boost to get its primary move off faster, use a choice scarf, and if you think it gets OHKO'd too easily, use a focus sash. Sash and scarf should always be utilized no matter what your team looks like.
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Darmanitan
Thrash
Overheat
Flare Blitz
Hammer Arm
Item: Flame Plate
This is a somewhat legit Pokemon. Again, go with protect and a fire gem here. Thrash isn't a great move...And overheat doesn't work as far as his strengths go. He's an Attacker, not a Sp Attacker. Flare Blitz is his key move, that should definitely stay. Hammer Arm could be a good filler.
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Haxorus
Dragon Tail
Dragon Claw
Hyper Beam
Dragon Pulse
Item: Draco Plate
Another legit Pokemon. This is a good one to scarf if you can afford it.
As far as moveset goes, I'd say you should definitely limit it to Dragon Claw for dragon-type moves. The other ones are completely unnecessary. Also, Hyper Beam is a Sp Att move...so it wouldn't do anything. Hax is a pure attacker. No Sp Att ANYWHERE.
He also is a good Rockslider. That's a key move in this metagame.
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Boldore
Explosion
Iron Defense
Rock Slide
Stone Edge
Item: Stone Plate
I'll trade that and trade it back for a Gigalith, first of all.
I actually like the moveset...just get rid of iron defense for protect.
Stone plate...meh. Go with either a rock or normal gem.
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Tornadus
Fly
Air Slash
Toxic
Agility
Item: Sky Plate
Fly? Not necessary, acrobatics takes care of that in a heartbeat. Air slash is SP ATT, not many people use Tornadus for that. Go with a Tailwind instead to give your team a speed boost. Also, Toxic isn't necessary if you're not a staller. Go with Taunt if you want to shut someone down harder. Also, agility isn't really needed, Tornadus is the fastest OU Pokemon in this metagame.
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Samurott
Hydro Cannon
Waterfall
Hydro Pump
Surf
Item: Splash Plate
Waaay too many water-type moves. This wouldn't be a bad Pokemon to Sash, either. It's an attacker...go with Waterfall, cut the other three moves. Also, put an Aqua Jet on it for priority. Ice Beam wouldn't be another bad move. Protect for the last one.
You're lacking some overall team fluidity too. I recommend you really hit up either Smogon's or Skarmbliss's servers on Pokemon Online and give it a test.
Looks like you've got an idea though for who to consider using.
GL HF and stuff.