Standard baton pass Ninjask to set up Salamance for a sweep. Depending on the opponent's opener, can boost Speed and attack at least two stages each w/ Swords Dance on first turn, take a hit and survive w/ Focus Sash, Speed Boost at end, and then Protect -> Baton Pass. Usually works as a good set-up, although Sandstorm inducers ruin the set-up. Likewise, unanticipated multi-hitters can ruin it, too.
#2 Salamance @Lum Berry
EV: 252 Attack / 252 Speed / 4 HP
Fire Fang Earthquake
The goal is for Salamence to receive Ninjask's stat boosts, although not always possible. So, Dragon Dance is used if the situation calls for it. Earthquake and Fire Fang hit for super effective against common threats in OU, while few can stand up to a boosted Outrage. Lum Berry cures confusion at the end and lets the rain of death continue.
#3 Cloyster @White Herb
Ability: Skill Link
EV: 252 Attack / 252 Speed / 4 SpAtk
Second sweeper and potential opener, again depending on the opposing team. Set up with Shell Smash and destroy. Rock Blast helps destroy sun teams.
#4: Espeon @Light Clay Ability: Magic Bounce
EV: 252 HP / 252 Speed / 4 Def
Hidden Power Fighting
Dual Screens Espeon for added defense w/ Magic Bounce serving as an alternative to a rapid spinner. Psyshock as the main offense w/ HP Fighting for Dark-types, especially Tyranitar.
#5: Magnezone @Air Balloon
Ability: Magnet Pull
EV: 252 SpAtk / 220 Speed/ 36 HP
Hidden Power Fire
Magnezone basically serves one or two purposes. First, he traps and One- or Two-Hit KO's Forretress and Ferrothorn with HP Fire. Second, he can hide behind a substitute and hit with either STAB, depending on the switch-in. Thunderbolt takes out Cloyster and other Water Types while Flash Cannon hits Tyranitar, which is brought in as an intended counter with Fire Blast.
#6: Gliscor @Toxic Orb
Ability: Poison Heal
EV: 252 HP / 184 Def / 72 Speed
Gliscor serves as a physical wall with a potential to sweep, either via intercepting Ninjask's Baton Pass or using his own Swords Dance.
Some problems I've been having running this setup:
Cloyster and Gliscor's descriptions are sparse, but I'm going to let it go.
First off I find that this team is very slow pacedwhich is very problematic for such a high paced metagame right now. What I mean is that for your team to actually be threatening, you're going to need to set up with Ninjask and Baton Pass to something, set up with Salamence, set up with Cloyster, set up Dual Screens with Espeon, etc. During those turns of set up, your opponent can easily set up, or they can repeatedly attack you so that you have no chance of even attacking. Another thing to note is that your team happens to be very Rock weak, meaning things like Terrakion and Expert Belt Landorus are very threatening once Gliscor is down (in Landorus' case, he can just Hidden Power Ice to OHKO Gliscor). Mamoswine can just run straight through this team because 2/3 of your team is either weak to Ground or Ice, and the two that aren't don't resist them either. You also lack Stealth Rock, which is a must for just about every team and is crucial to gaining specific KOs on your opponents.
I would first off ditch Ninjask. I would go off to call it worthless on a any team that's not a full blown Baton Pass team. It's part of the reason why your team is slow paced (ironic that Ninjask has Speed Boost and a very high speed stat, but it's true) and doesn't help at all against Terrakion or Landorus. It doesn't learn Stealth Rock either, so three things there that I've outlined in the beginning paragraph and Ninjask fits all those areas of bad. Instead, I would recommend using something like Choice Band Scizor to take down pesky Pokemon like Latios, Terrakion, Landorus, and most importantly, Mamoswine.
Dragon Dance Salamence is honestly "meh" on your team. Scarf Salamence would fit much, much better. Your team lacks anything to revenge kill the likes of Volcarona and Dragonite. Ninjask doesn't count, because it takes turns to bring its speed up and during that time, the opponent can raise their speed too. Not to mention that Ninjask can't do anything to hurt the two, and Baton Passing would lead to swift death to whatever is brought out. With Scarf Salamence, not only do you get a "ready to go" sweeper, but you get a decent revenge killer in one.
With that said, Salamence isn't exactly the greatest revenge killer out there (but by no means is it bad). There are things, like Ice Shard, Scarf Landorus, and Scarf Keldeo, that will outspeed Salamence and be able to take it down rather easily. So it's recommended to have some sort of complement to Salamence. Scarf Latios would be my main choice, as it is a fairly decent check to Keldeo, Terrakion, and Landorus. Much like Salamence, it can sweep pretty easily once his counters have been removed (thanks to Magnezone). Because Latios and Espeon have similar typings, it's recommended to take out Espeon so that you won't have too many Sucker Punch and U-turn weak Pokemon around.
I would make a switch from Gliscor to Skarmory, and give that Skarmory Stealth Rock instead of the usual Spikes. The reason being is that Skarmory handles Mamoswine much better than Gliscor (for obvious reasons), and Mamoswine is still a threat even if you have Scizor to check it. The other threats, like Terrakion that can't be suppressed with Skarmory, are checked by your other mons so you don't have to worry about it that much. Skamory provides the ever important Stealth Rock to your team, as well as providing a nice defensive switch in to quickly block the attacks of Scizor and Tyranitar when you need to.
Scizor @Choice Band Technician 248 HP, 252 Atk, 8 Spe