445 Garchomp

Garchomp has two distinct playstyles based on its fast move:

Mud Shot’s fantastic energy gain combined with two very powerful (but expensive) charged moves in Earth Power and Outrage make Garchomp a terrifying threat. It is at its best when the opponent has no shields, so it should be saved until the end of a game as a closer. Notably, though, you can exchange Earth Power out for Sand Tomb, trading some of that incredible nuke potential for the ability to actually perform while shields are up. Earthquake is stronger than Earth Power and has higher Damage Per Energy, but Earth Power is preferred for its lower cost. Fire Blast is largely inefficient and outclassed, although it can deal significant damage to Togekiss. Do not use mono-Ground Garchomp.

Dragon Tail is a solid move thanks to the GBL Season 8 update, and provides Garchomp with a significant amount of fast move pressure, contrasting the charge move focus of the previous moveset. Sand Tomb is a necessary complementary move - not only for its low cost, but also because the Defense drop immediately benefits Dragon Tail. Outrage can be used to nail Flying types so that Garchomp isn't entirely reliant on Dragon Tail to dent them, but Earth Power can dent Zacian and burst down Steel types. Earthquake and Fire Blast are costly options that are comparatively unreliable because of Dragon Tail's average energy gain.

While Garchomp has a super strong collection of moves, the fact that it loses to so many top tier Pokémon (Azumarill, Medicham, Altaria, Deoxys-Defense, Cresselia, and to a lesser degree Venusaur and Skarmory) make it all but unusable down in Great League.

Fantastic shields-down matchups against both Steels and Dragons make Garchomp a pretty strong and versatile choice in Ultra League, though if you just want a Dragon-type or a Ground-type, there are more popular picks.

Garchomp has excellent stats and packs a nearly unresisted STAB combination that it can utilize somewhat reliably, making it a devastating threat in the Master League. It notably causes problems to the Giratina + Steel-type core as it can hit both Pokemon super effectively. Dragon Tail Garchomp is notable for its ability to reliably beat Melmetal, something other Dragon Tail or Dragon Breath Pokemon may struggle to do consistently. Mud Shot Garchomp can wreak havoc when shields are down, notably smashing apart both Giratina and Dialga.

The biggest roadblock to Garchomp is Togekiss, who completely and utterly walls it unless Garchomp has Fire Blast, and even then it still loses hard. Its weakness to Dragon is a problem due to how common Dragon Breath and Dragon Tail are, with Lugia and Dialga being those that will outdamage Garchomp in a fast move contest. Zacian is a major problem, especially against Dragon Tail variants. Garchomp's double Ice weakness can leave it vulnerable to Mamoswine and Ice Beam Mewtwo.

It is important to note that Garchomp has a bulkpoint against Dialga, Zekrom, and Reshiram's Dragon Breath if it has at least 14 Defense IV and is at an equal level. Since Dialga is often Best Buddied, Garchomp should also try to match the Best Buddy if possible, or else Dragon Breath will deal significantly more damage.