This team was based off a Gen 8 team, where it featured the same strategy as this. I've tried to shift this strategy to USUM, and for me it works pretty well.
Excadrill (F) @ Choice Band
Ability: Sand Rush
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Earthquake
- Iron Head
- Rock Slide
- Fling
Excadrill is the main damage dealer of this team, and with support with Gravity; Earthquake only resists Grass/Bug. If Gravity isn't set up, Iron Head/Rock Slide works well to damage the resistances to ground. Fling is used where the power of Choice Band is not needed. Although risky to use, getting rid of the Choice Band allows Excadrill to damage opposing Pokémon more efficiently.
Hippowdon (F) @ Eject Button
Ability: Sand Stream
EVs: 252 HP / 108 Def / 144 SpD / 4 Spe
Impish Nature
- Stealth Rock
- Slack Off
- Earthquake
- Stone Edge
Hippowdon is the first Sand Stream user of the team, which packs Stealth Rock support. The Eject Button is used to tank a hit, and effectively switch out to Excadrill/Pidgeot to deal with the Pokémon at hand. Stone Edge is preferred over Whirlwind to chip Flying types when Gravity is not up.
Gigalith (M) @ Eject Button
Ability: Sand Stream
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Gravity
- Rock Blast
- Earthquake
- Explosion
Gigalith is the first Gravity user and the second and last Eject Button user to abuse Excadrill's power. It acts as a fully special wall to tank attacks. Explosion is used for when the Eject Button is used to switch in Excadrill in a pinch.
Ferrothorn (M) @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 4 Atk / 252 Def
Relaxed Nature
IVs: 0 Spe
- Gravity
- Leech Seed
- Knock Off
- Gyro Ball
Ferrothorn acts as a fully defensive wall, and is the second and last Pokémon to use Gravity. Ferrothorn is used to quad resist Grass moves in which Hippowdon/Gigalith cannot handle. Leech Seed + Leftovers ensures Ferrothorn to regain the most amount of HP without Protect. Knock Off is used to remove items, and aims to Knock Off Choice Scarf Pokémon that outspeeds Excadrill under sand. Gyro Ball is used to hit Grass types for the most damage opposed to Power Whip.
Tapu Fini @ Icium Z
Ability: Misty Surge
EVs: 248 HP / 32 Def / 156 SpD / 72 Spe
Calm Nature
IVs: 0 Atk
- Defog
- Nature's Madness
- Brine
- Haze
Tapu Fini is used as a mixed wall to deal with the likes of Greninja, along side Ferrothorn to scout for Gunk Shot. Haze is used alongside Icium Z to reset stats and to regain full HP in a pinch. Nature's Madness deals a huge chunk to all Pokémon, in where Brine can also do massive damage because of Nature's Madness (and Stealth Rocks if they are up).
Pidgeot (F) @ Pidgeotite
Ability: Big Pecks
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Hurricane
- Heat Wave
- Roost
- U-turn
Mega Pidgeot is used to deal with Grass/Bug types Excadrill can't deal with, with 100% accurate Hurricanes and Heat Waves. Its above-average speical attack is used to chip down defensive Pokémon that Excadrill cannot power through. U-turn is used to gain momentum, and Roost is used to increase survivability.
Here's a paste of the team to see the movesets of all the Pokémon without the explanations.
https://pokepast.es/2a5e7ce280bc65c0
Excadrill (F) @ Choice Band
Ability: Sand Rush
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Earthquake
- Iron Head
- Rock Slide
- Fling
Excadrill is the main damage dealer of this team, and with support with Gravity; Earthquake only resists Grass/Bug. If Gravity isn't set up, Iron Head/Rock Slide works well to damage the resistances to ground. Fling is used where the power of Choice Band is not needed. Although risky to use, getting rid of the Choice Band allows Excadrill to damage opposing Pokémon more efficiently.
Hippowdon (F) @ Eject Button
Ability: Sand Stream
EVs: 252 HP / 108 Def / 144 SpD / 4 Spe
Impish Nature
- Stealth Rock
- Slack Off
- Earthquake
- Stone Edge
Hippowdon is the first Sand Stream user of the team, which packs Stealth Rock support. The Eject Button is used to tank a hit, and effectively switch out to Excadrill/Pidgeot to deal with the Pokémon at hand. Stone Edge is preferred over Whirlwind to chip Flying types when Gravity is not up.
Gigalith (M) @ Eject Button
Ability: Sand Stream
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Gravity
- Rock Blast
- Earthquake
- Explosion
Gigalith is the first Gravity user and the second and last Eject Button user to abuse Excadrill's power. It acts as a fully special wall to tank attacks. Explosion is used for when the Eject Button is used to switch in Excadrill in a pinch.
Ferrothorn (M) @ Leftovers
Ability: Iron Barbs
EVs: 252 HP / 4 Atk / 252 Def
Relaxed Nature
IVs: 0 Spe
- Gravity
- Leech Seed
- Knock Off
- Gyro Ball
Ferrothorn acts as a fully defensive wall, and is the second and last Pokémon to use Gravity. Ferrothorn is used to quad resist Grass moves in which Hippowdon/Gigalith cannot handle. Leech Seed + Leftovers ensures Ferrothorn to regain the most amount of HP without Protect. Knock Off is used to remove items, and aims to Knock Off Choice Scarf Pokémon that outspeeds Excadrill under sand. Gyro Ball is used to hit Grass types for the most damage opposed to Power Whip.
Tapu Fini @ Icium Z
Ability: Misty Surge
EVs: 248 HP / 32 Def / 156 SpD / 72 Spe
Calm Nature
IVs: 0 Atk
- Defog
- Nature's Madness
- Brine
- Haze
Tapu Fini is used as a mixed wall to deal with the likes of Greninja, along side Ferrothorn to scout for Gunk Shot. Haze is used alongside Icium Z to reset stats and to regain full HP in a pinch. Nature's Madness deals a huge chunk to all Pokémon, in where Brine can also do massive damage because of Nature's Madness (and Stealth Rocks if they are up).
Pidgeot (F) @ Pidgeotite
Ability: Big Pecks
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Hurricane
- Heat Wave
- Roost
- U-turn
Mega Pidgeot is used to deal with Grass/Bug types Excadrill can't deal with, with 100% accurate Hurricanes and Heat Waves. Its above-average speical attack is used to chip down defensive Pokémon that Excadrill cannot power through. U-turn is used to gain momentum, and Roost is used to increase survivability.
Here's a paste of the team to see the movesets of all the Pokémon without the explanations.
https://pokepast.es/2a5e7ce280bc65c0