Soo,fought Alder, almost fullfilled the unova dex, caught Latias, Got Reshi & Kyurem, reached Area 5 on White Treehollow, here is my (failed?) team:

Emboar L65 F @
Expert Belt
Don't care, Blaze
EVs: ??
-
Flamethrower
-
Scald / Rock Slide
-
Wild Charge
-Hammer Arm
So first of all, something I noticed with your team is that on a lot of your Pokemon, you have two or three moves of the same type, which is really a waste of a moveslot as it limits the amount of coverage you can deal. You don't need more than one move of any type unless each move serves a distinct purpose, and for Emboar, that's not the case. I'd go with Flamethrower for your STAB move as it's reliable and doesn't have any major drawbacks. Keep Hammer Arm for your Fighting-type STAB; Emboar doesn't mind the speed drop that comes with Hammer Arm since he's pretty slow anyway. Go with Wild Charge for a powerful move to hit Water-types. Scald is nice to hit other Fire-types from the special side of things, whereas Rock Slide pairs well with Hammer Arm and can also hit other Fire-types from the physical side. Expert Belt for the item, as with this set you'll likely be able to score super-effective hits.

Samurott L62 M @
Leftovers
Torrent
-Surf
-
X-Scissor
-
Ice Beam
-
Return
This is a good example of what not to do. With three Water-type moves and Focus Energy, what are you going to do if Samurott is your last Pokemon and you're facing another Water-type, or a Grass-type? That's why having diversity with your moves is important. Personally I'd stick with Surf as your STAB move as it's a great and reliable move, though Waterfall is also quite good. Don't go with Hydro Cannon though as you have to recharge after using it, leaving you fully vulnerable for a turn. X-Scissor to hit Psychic-, Dark- and Grass-types, and Ice Beam for added coverage. Return is a good move as it rounds out the set with some nice neutral coverage. Since Mystic Water only powers up Water-type moves (ie only Surf on this set), you can go with Leftovers as recovery is always nice, or even Life Orb if you feel you need more power.

Jolteon L70 M @
Wise Glasses / Leftovers
Volt Absorb
-
Thunderbolt
-
Signal Beam
-
Shadow Ball / Charge Beam
-Thunder wave
/ Substitute
I don't really need to go over the whole "give your Pokemon a variety of moves" thing again, but notice how with your set you'd be completely walled by Ground-types? Keep Thunderbolt as your Electric-type move as it's a reliable and powerful STAB move. Signal Beam can be used for coverage as it hits Grass-types, who resist Electric, for super effective damage, and also gives you a way to hit Ground-types. For your final two moves, you have two options. You can either go with Shadow Ball for added coverage, and Thunderwave for team support, or you could use the combination of Substitute and Charge Beam. If you go with the second option, this gives Jolteon a means of setting up; use Substitute and then spam Charge Beam, racking up Special Attack boosts, and you can then proceed to sweep through teams with powerful Thunderbolts and Signal Beams. If you go with this option, give Jolteon Leftovers for recovery. If you go with Shadow Ball, though, Jolteon would prefer Wise Glasses for more power.

Serperior L64 F @
Leftovers
Overgrow
-
Coil
-
Aqua Tail
-
Outrage
-Leaf Blade
More coverage once again. Coil is a nice move which allows Serperior to set up, which is especially important since its offences aren't really that spectacular. I've given you a purely physical set here to make the best use of Coil. Leaf Blade is your STAB move of choice, being a powerful and reliable physical Grass-type move that therefore gets boosted by Coil. Aqua Tail lets you hit Fire-types hard, and Outrage is a move you can use in sticky situations for added power and coverage. Leftovers is your item here for more recovery.
An alternative set is to go down the Subseeding route.
Serperior @ Leftovers
Overgrow
~ Substitute
~ Leech Seed
~ Giga Drain
~ Aerial Ace / Toxic / Dragon Tail
The strategy here is to use Substitute and Leech Seed to stall and heal off damage. Giga Drain is also used as a STAB move and helps you drain even more HP from your opponent. With Leftovers attached, Serperior will be difficult to take down. That said, Grass-types are a big problem for this set as they are immune to Leech Seed, so you might want to use Aerial Ace as your last move to deal with them, or go with Toxic as a move which not only hits Grass-types, but can be used on all Pokemon (apart from Poison- and Steel-types) to further deplete their HP. Another option is to go with Dragon Tail, to just get rid of the opponent if they're a Grass-type.

White Kyurem L71 @
Choice Specs / Wise Glasses / Leftovers
Turbo Blaze
-Ice Beam
-
Earth Power
-Dragon Pulse
/ Draco Meteor
-Fusion Flare
Ice Beam > Ice Burn as Ice Beam is still powerful (especially coming off Kyurem-W's ridiculous SpA stat) and doesn't require a turn of charging up, so thus is more powerful than Ice Burn over two turns. Go with Earth Power to hit Steel- and Fire-types hard. An option for your Dragon-type STAB is Draco Meteor, but Dragon Pulse is, much like Ice Beam, still extremely powerful. Choice Specs or Wise Glasses both increase your Special Attack, with Choice Specs increasing it by 50% (and locking you into one move) compared to Wise Glasses's 10%, but Leftovers might be the better choice as you might find Kyurem-W doesn't really need the extra power from its item.
Flygon L65 M @
Life Orb / Leftovers
Levitate
-Earth Power
/ Earthquake
-Fly
-
Fire Punch / Flamethrower
-Dragon Claw
Not a whole lot to say here. Earthquake is an option over Earth Power, and in the end it just comes down to personal preference. Go with Fire Punch or Flamethrower > Crunch, as Flygon needs a way to effectively deal with Ice-types. Life Orb can be used as your item to power up all your moves, or you can go with Leftovers for healing.
That's pretty much my team, I was wondering if I should change Kyurem (For a Psychic or Ghost type), since I've already got a dragon type and it helps much more than Kyurem.
Really? That's interesting, I would've imagined Kyurem would be more powerful than Flygon on your team. Have you got any Psychic- or Ghost-Pokemon in mind?