Gliscor @ Choice Scarf
Impish – 216 HP, 176 Speed, 116 Def
Hyper Cutter / Sand Veil
~ Knock Off
~ Aerial Ace
~ U-Turn
~ Earthquake / Stealth Rock

A set specifically designed for a lead Gliscor. It has enough Speed to outpace Choice Scarf Heracross and even without any Atk EVs, Aerial Ace is a guaranteed OHKO on a 4HP/min Def Heracross. Obviously, most Heracross leads will switch upon sight of this, but for later in the game, Aerial Ace might save your ass against that very same Heracross. U-Turn is one of the best moves in the game on a fast lead, and given that this isn’t afraid of taking a boosted Pursuit from a Weavile or CB Tar, you don’t have to worry about outspeeding any of them.

U-Turn simply allows you to scout for what your opponent does (i.e. stay in or switch), giving you the opportunity to switch to an appropriate counter, while dealing some nice damage at the same time (instantly disabling any Focus Sash leads). If you expect a switch (a possible scenario when facing a Heracross), you can use Knock Off to disable the incoming pokemon’s hold item right away. Even if the pokemon decides to stay in, you’ll still get rid of his item. The fourth slot depends on preference: an early Stealth Rock can be incredibly helpful, but it really limits Gliscor’s uses later in the game. Earthquake is therefore most likely the better choice.

The EV spread gives equal HP and Def, enabling you to take physical hits optimally. Like said earlier, you hit 270 Speed, so you can outspeed all Hera leads (except for the occasional Jolly Choice Scarf ones). An alternative would be to go even higher to 285 Speed, to get the first strike even when facing a Jolly Choice Scarf Medicham.

Gliscor @ Leftovers
Impish – 252 HP, 252 Def, 4 Speed
Hyper Cutter / Sand Veil
~ Knock Off / U-Turn / Roost
~ Stealth Rock / U-Turn / Screech
~ Earthquake
~ Ice Fang / Stone Edge / Aerial Ace / Roost

Support Gliscor. Max HP and max Def let him take a whole lot of physical hits, while he can Knock Off the items of switch-ins. Stealth Rock is always a nice move to have, and Roost gives him a reliable way to recover his HP. Earthquake is one hell of a solid move here, as it gives Gliscor something to threat other pokemon. Even with no Atk EVs, an attack with 100 base power that's getting STAB is nothing to laugh at.
As for your last moveslot, there is room for some more offense through either one of Ice Fang, Stone Edge or Aerial Ace, of which Aerial Ace would be preferred to, aside from absorbing hits from Heracross, take it down as well.

U-Turn can be considered over Knock Off or Stealth Rock, as it allows Gliscor to take the hit from a physical sweeper, then pass on to a glass cannon (or something else of course) to allow it a safe switch-in, possibly setting up for a revenge kill. Knock Off is still pretty much a staple here to ruin incoming special sweepers, especially the Specs'd ones. Screech is another option on your second moveslot, as it enables you to hit a bit harder when necessary (although that shouldn't be your first priority) and it can help forcing switches, which makes Knock Off even funnier to use here.

Gliscor @ Leftovers
Impish – 244 HP, 168 Atk, 96 Def
Hyper Cutter
~ Swords Dance
~ Stone Edge
~ Earthquake
~ Roost / Taunt / Agility

An offensive tank. After a Swords Dance, you’ll have enough Atk to OHKO the standard Choice Band Metagross (the most defensive one, with 252 HP/16 Def EVs), the standard Starmie (0 HP/40 Def EVs) so now it can’t safely switch in on you, the standard Dragon Dance Tyranitar (108 HP/0 Def), the standard Salamence (Hyper Cutter prevents Intimidate) and you will 2HKO a Dusknoir with a +Def nature, 252 HP EVs and 116 Def EVs (about the most defensive you will ever see).

As you can see, Swords Dance is a very important thing here. If the opponent switches to something like Starmie on the very first sight of Gliscor, you won’t have enough time to set up Swords Dance and take it down with an Earthquake afterwards, and the same goes for incoming Dusknoir, who will still have a chance to burn you with Will-O-Wisp. Take that into account.

The 244 HP EVs bring your HP to 352, a magical number for Leftovers recovery. The remainder was dumped in Def for some more survivability. As you can see, Speed was completely neglected. I did this because you really need those EVs in Atk, Def and HP. Still, you can choose to make this a bit less defensive so you can opt to go for some Speed.

Roost in the final slot will give you some more survivability and is definitely recommended if you are going for a defensive approach. Taunt is another option for a more speedier version; Roost will be less effective to begin with, on such a set, and you can Taunt more things that fall under your Speed to prevent them from inflicting a status effect upon you. Even with the defensive spread, it still helps against the likes of Weezing, Dusknoir and Tangrowth.

Agility is another option, but using two stat-boosting moves on one set without Baton Pass on there as well is a bit suicidal. Gliscor most likely won’t have the time to set up both, but it’s always worth a try.

Gliscor @ Choice Band
Adamant – 252 Atk, 236, 20 Def
Hyper Cutter
~ Ice Fang / Thunder Fang / Aerial Ace / Night Slash
~ Earthquake
~ Stone Edge
~ U-Turn

Like with all things with a respectable Atk stat, a Choice Band can be slapped upon them to make them a nice physical sweeper. Gliscor is no exception. Adamant and max Atk are required, since without it, this really isn’t that threatening. With 236 Speed, you’ll outspeed max Speed, Jolly base 80 Speed pokemon (Medicham for example) and the 20 Def EVs make your HP and Def equal to each other (291), so that you’ll still be able to absorb physical attacks nicely.

As for the attacks themselves, Aerial Ace isn’t really necessary here, but I can see it as a means to take down Heracross, so I still listed it as an option over Ice Fang and Thunder Fang. Ice Fang is a nice way to deal with the Dragon/Flying or Dragon/Ground pokemon out there and it takes down Breloom and Torterra, two things that resist both Earthquake and Stone Edge, down quite effectively at the same time. Thunder Fang’s only real use is taking down Gyarados, but that certainly is something that you should take into consideration. Against the bulkiest Gyarados out there, it’ll do 97.4% damage at minimum, so that’s almost a guaranteed OHKO.

Earthquake is a must on here and Stone Edge pairs up nicely with it, and is a solid attack in itself. Keep in mind that Stone Edge alone is enough to OHKO Salamence (assuming 4 HP/0 Def EV spread), so don’t pick Ice Fang because you want to OHKO Salamence. Finally, U-Turn. It’s just an amazing move. If you predict a switch and have no idea to what, just U-Turn to deal a respectable amount of damage and switch to a counter afterwards.

Gliscor @ Life Orb / Muscle Band
Adamant – 252 Atk, 236 Speed, 20 Def
Jolly – 252 Atk, 204 Speed, 52 HP
Hyper Cutter
~ Swords Dance
~ Earthquake
~ Stone Edge
~ Ice Fang / Thunder Fang / Aerial Ace / Baton Pass / Taunt / Night Slash

A fully offensive Swords Dance sweeper. The first EV spread is the same as the Choice Band one, the second allows you to outspeed Adamant Garchomp and everything slower than that, but you lose some Atk because of the change in nature.

Try to get up a Swords Dance as soon as possible, to become an actual threat to your opponents. Earthquake and Stone Edge for type coverage, with the last moveslot depending on preference. Baton Pass makes sure you can do something beneficial with the Swords Dance when you are being stopped in your tracks by an opponent’s pokemon, Taunt prevents you from being phazer or burned and the other attacks can add some more type coverage.

Gliscor @ Leftovers
Impish – 252 HP, 252 Def, 4 Speed
Hyper Cutter / Sand Veil
~ Agility / Swords Dance
~ Earthquake / Aerial Ace
~ Baton Pass
~ Roost / Substitute

Baton Passing Gliscor. The concept is simple, just use Agility or Swords Dancewhen you see the chance, Roost when you need to restore damage and Baton Pass when you think the time is right. Earthquake or Aerial Ace is there to have some sort of offense left, it’s up to you which one you choose.

You can choose Substitute over Roost if you want, so that you can scout for what your opponent switches into you: you can always just use your stat-boosting move of choice afterwards, on the turn your Sub is broken, but if you think you’re faster already, you have just created another something you can pass along, so you can give something else on your team a free switch-in.



Other options: Counter, Toxic, Brick Break
There aren’t a lot of other options for Gliscor. Counter can be a fun move to toy around with, Toxic can be used on a more stalling-based set, combined with Protect and Leftovers for example and Brick Break is another option on most of the sweeping-orientated sets, but the coverage provided by Stone Edge and Earthquake makes Brick Break a bit unnecessary at times.

QUOTE

U-Turn is one of the best moves in the game on a fast lead, and given that this isn?t afraid of taking a boosted Pursuit from a Weavile or CB Tar, you don?t have to worry about outspeeding any of them.