Let me rate this too. I think I can give some good advice.
Jolteon
I completely agree with his set. Life orb is the way to go, because of the good coverage Jolteon can get. Since he carries volt switch, he'll be able to switch out when the time is right while taking a chunk out of the opponent. You don't want him locked into T-Bolt when there is a big chance the opponent has a EQ STAB Ground type just waiting for his chance to set up on you.
Scizor
OK, being that this is my favorite sweeper of all time, I take it as my personal responsibility to give you the best set possible. Here it is:
Trait: Technician
EVs: 252 HP/ 252 Atk/ 4 Spe
Nature: Adamant (+Atk, -SpA)
-Bug Bite
-Swords Dance
-Bullet Punch
-Superpower
Basically, the object is to sword dance as much as you can, and then bullet punch everything. Bug bite is like a physical form of bug buzz with technician. Superpower takes care of steels looking to wall. Trust me, this works.
Virizion
Alright, I don't use this guy that much, but I see what you're looking for is a sweeper, and a close combat abuser. Frankly, Virizion's attacking stats just aren't super great compared to the other sweepers in OU. However, Virizion has a close friend that she'd like you to meet....
Terrakion @ Choice Band
Trait: Justified
EVs: 252 Atk/ 252 Spe/ 4 Def
Nature: Jolly (+Spe, -SpA)
-Close Combat
-Stone Edge
-Earthquake
-X-Scissor
This guy is really strong with a choice band. He's one of the fastest in OU, so his ability to sweep is pretty good. Close Combat will be your main sweeping move. X-Scissor takes care of Psychics resisting Close Combat, and Gengar is easily 1HKO'd by Stone Edge. He works.
Volcarona
OK, for a more effective bulky sweeper, try this EV spread: 144 HP/ 252 SpA/ 112 Spe
With that you'll be able to take more hits, which is nice because Volcarona already has some nice natural bulk. HP rock isn't super important, so give him Giga Drain to hopefully KO some water/rock types after a couple o' quiver dances.
Dragonite
For the most part this guy looks pretty good. For a rooster you should give him leftovers though. You could also try more attack with this spread: 112 HP/ 252 Atk/ 144 Spe as it will prove to make him stronger. I'd also make him Adamant since you'll get his speed up via Dragon Dance anyway.
Gyarados
OK, I like Gyarados, but if you take a close look at your team, you'll see that it's composed of mostly sweepers. You already have a D-Dancer, so let me suggest something that will help your team in the long run.
Tentacruel @ Black Sludge
Trait: Liquid Ooze
EVs: 252 HP/ 252 Def/ 4 SpD
Nature: Bold (+Def, -Atk)
-Rapid Spin
-Toxic Spikes
-Giga Drain
-Protect
Alright, like B3N said, you have a huge stealth rock weakness. Tentacruel, IMO is one of the best Rapid Spinners. Not only can he Rapid Spin, but he can put out Toxic Spikes of his own. With liquid ooze he walls a giga-draining Volcarona, and with protect he can regain some HP and stall the opponent if he has been poisoned by T-Spikes.
Have fun in OU!
