Moves
This is the Garchomp to use if you want to take advantage of its versatility and mind game-playing power! Earthquake is Garchomp's strong, reliable STAB move and its way of tearing up Steel-types. Outrage is riskier because it locks Garchomp in, but it provides an immense amount of immediate power and slams Levitate users and Flying-types particularly hard. The third moveslot is generally open for one of Garchomp's support moves. While Stealth Rock can be a bit difficult to use in Battle Spot Singles, Garchomp is one of the best users of the entry hazard thanks to its reasonable bulk and offensive presence. Swords Dance, on the other hand, gives Garchomp potent sweeping power, especially late-game! A third option is Toxic. While Toxic may seem like an oddball choice on an offensive Pokemon, running it on Garchomp can be an effective way to cripple Porygon2 and Cresselia.
The fourth moveslot is where the customization begins full force! Rock Tomb might seem rather weak, but in addition to smashing Talonflame without locking Garchomp into Outrage, it provides speed control, which can screw up desperate Garchomp switch-ins such as Greninja. If you prefer slightly more power and the ability to cause foes to flinch, Rock Slide is a reasonable alternative. Stone Edge is Garchomp's most powerful Rock-type attack, but it comes with the cost of having the highest miss rate.
If Rock-type moves don't fit your team, Dragon Claw gives Garchomp a reliable Dragon-type STAB move to hit weakened foes such as Mega Salamence and Hydreigon. If you run Swords Dance, Dual Chop becomes the more attractive option, because unlike Dragon Claw, Dual Chop can smash through Focus Sash Pokemon after a boost. Just note, opposing Rocky Helmet users become more of an issue when running Dual Chop, and it has a 10% chance to miss. While not particularly strong, Fire Blast is also a good option, as it 2HKOes Skarmory and Ferrothorn. Finally, if you just can't decide between Stealth Rock and Swords Dance, using both is actually a viable possibility, giving Garchomp both early-game and late-game utility. However, this comes at a serious cost: you will have to choose between making Garchomp far easier to revenge kill due to Outrage and severely reducing Garchomp's immediate power with Dual Chop.
Set Details
Garchomp's given nature and EVs maximize its Speed and Attack, while Rough Skin allows Garchomp to get some extra damage in via switching into contact moves (especially painful in Mega Kangaskhan's case). If you want a bit of extra power for Fire Blast and aren't using a Yache Berry, feel free to use a Naive nature.
There are many items to choose from for this Garchomp. While Focus Sash might seem a bit strange to use considering Garchomp's bulk, Garchomp still happens to be one of the most effective Focus Sash users in the game, thanks to its sandstorm immunity and offensive power! This item gives Garchomp an edge against many foes early-game, especially if you need to set up Stealth Rock. If you manage to hold onto Focus Sash later in the game, Garchomp can act as an emergency check to many offensive threats and can even set up a surprise Swords Dance, potentially devastating your opponent's team! If you want Garchomp to have more late-game value, Lum Berry is an excellent choice. A common way to deal with Garchomp is to burn it with Pokemon such as Rotom-W. With Lum Berry and Swords Dance, Garchomp can set up on and devastate some of these threats when they are weakened. It also allows Garchomp to act as an emergency Spore absorber against Breloom. If you want to take advantage of Rough Skin, consider using Rocky Helmet Garchomp. With a Rocky Helmet in tow, most Pokemon will take 24% damage from touching Garchomp, which can be enough to push some foes into its KO range. In particular, Mega Kangaskhan takes a devastating 58% damage, which can potentially save you from this fearsome monster! If you thirst for more specialized luring power, Yache Berry should be on the top of your list. Most non-STAB Ice-type moves will fail to OHKO Garchomp when it holds a Yache Berry, allowing Swords Dance Garchomp to potentially smash through some of its checks! If you are more worried about faster Dragon-types, Haban Berry can work as well. Finally, if you just want to give Garchomp some added bulk, Leftovers can work just fine. Just remember, Leftovers will give away Garchomp's item immediately, reducing its mind gaming power.
Usage Tips
If you're using Garchomp as a lead, Focus Sash is recommended, as it gives Garchomp the edge versus possible leading checks such as Life Orb Greninja. Try to set up Stealth Rock if your opponent has Pokemon that are greatly harmed by entry hazards, such as Focus Sash Breloom and Talonflame. Regardless of what Garchomp variant you are using, just try to do as much lasting damage to the opponent's team as possible. As long as Garchomp doesn't get KOed before it can do any damage, it will usually have done its job. Just make sure that, when using Garchomp earlier in the game, you don't overly rely on Garchomp to defeat a certain threat!
If you plan on using Swords Dance, Garchomp usually becomes more effective later in the game. The key to making Garchomp a sweeping force late-game is to try as hard as possible to keep Garchomp's item hidden. Garchomp is at its most dangerous when your opponent has as little information as possible, as your opponent guessing Garchomp's item incorrectly can lead your team to victory! Tactics to maximize Garchomp's luring power include scouting your opponent's team for their Garchomp checks and switching Garchomp into attacks that don't give away its item, such as Electric-type moves.
Team Options
This Garchomp set is extremely easy to fit on most teams, thanks to its versatility. While Garchomp will enjoy teammates that can take care of foes such as Porygon2, Cresselia, Greninja, and Mega Salamence, the point of this set is less about being the star of your team and more about supporting your team in key ways. In general, you should pair Garchomp up with teammates that benefit from its item-based mind games. For example, using Focus Sash Garchomp can free up teamslots thanks to its increased checking power. Using Lum Berry Garchomp to smash through Will-O-Wisp-using checks is great news for physical attackers such as Mega Kangaskhan. Rocky Helmet Garchomp, on the other hand, pairs up well with Pokemon that fear Mega Kangaskhan. Finally, Yache Berry Garchomp tends to pair well with Pokemon that prefer having fast Hidden Power users such as Thundurus and bulkier Ice Beam users such as Porygon2 and Cresselia out of the way.
Most fast, offensive Pokemon will enjoy Stealth Rock support aiding their cleaning capabilities, especially Pokemon that want Talonflame and Charizard out of the way (as both take 50% from Stealth Rock). Offensive Fighting-types love Stealth Rock support, as having Talonflame out of way greatly increases their offensive presence, and they can even help deal with Porygon2 for Garchomp. Blaziken can switch into weak Ice-type attacks and provide potent sweeping power with Speed Boost, while Heracross is one of the few Fighting-types that can muscle past Cresselia for Garchomp. Aegislash helps deal with Cresselia, can switch into super effective attacks for Garchomp, and has an easier time sweeping weakened teams with Shadow Sneak when Stealth Rock is up. While it doesn't have as much synergy with Garchomp, Belly Drum Azumarill also appreciates Stealth Rock's support in getting the residual damage it needs to sweep a team.
While Swords Dance tends to be one of this set's more situational moves, supporting Garchomp's sweeping power is not a bad idea if you can fit in teammates for it. Paralysis support is a good idea no matter what item Garchomp is running, as paralyzing faster threats can conserve Garchomp's Focus Sash or, if running another item, simply make Garchomp even harder to check! Bulky Thunder Wave users such as Porygon2, Gyarados, and Ferrothorn will work just fine for this role. If you prefer a more direct answer to defensive Pokemon, Mega Gengar is one of the best teammates available! Shadow Tag allows Mega Gengar to toy with defensive threats through the use of tools such as Destiny Bond and Taunt, and it has the bonus of being able to wear down physical threats with Will-O-Wisp.