Low-Tiered Pokémon in 1v1

Sturdy, because of entry hazards, is generally deemed to be a mediocre ability in most tiers. In 1v1, however, Sturdy is one of the best abilities in the game, allowing the user to survive any one hit and hit hard back. As a result of this, numerous lower-tier Pokémon enjoy relatively high usage and viability in 1v1.

Donphan & Golem

Donphan and Golem are 1v1's go-to "Sturdymons". Both of them accomplish much the same roles with the combination of a STAB Earthquake, Sturdy, and base 120 Attack but with slight nuances in their niches. Donphan brings higher speed than Golem to the table, allowing it to outspeed Pokémon such as Mimikyu and non-maximum Speed Charizard after a Rock Tomb. Golem, however, may use Rock Blast to beat much of the same. Priority also affects the Pokémon that each can beat, with Donphan's Ice Shard being a good method to beat Pokémon like Garchomp and Golem's Sucker Punch being more useful against Pokémon like Meloetta. The final important difference is typing. While Golem has powerful Rock-type STAB moves, enabling it to beat Pokémon like Charizard more reliably, Donphan has a better defensive typing, allowing it to beat Fake Out attackers like Lopunny. Alternatively, either Pokémon may opt to use a Rockium Z in order to hard counter Charizard, with Donphan opting for Head Smash and Golem opting for Stone Edge in order maximize the power of Continental Crush, although Golem is the more viable user of this item. Donphan may also use a Choice Band, enabling it to beat Pokémon like Landorus-T, Jumpluff, Snorlax, Genesect, Ferrothorn, Primarina, and Tapu Fini with its boosted coverage moves.

Avalugg

While in 6v6, Avalugg's pitiful Special Defense holds it back, it uses this to its advantage in 1v1. The fearsome combination of Mirror Coat + Sturdy allows Avalugg to effortlessly KO a variety of special attackers, especially Choice-locked ones such as Genesect. Against physical attackers, however, Avalugg instead relies on its massive defense stat to simply outtank them. As a result, every good Avalugg runs Curse, Avalanche, and Mirror Coat. The item and last move are considered slight nuances per set more than anything. This Avalugg opts to use Groundium Z in an effort to soft check Mega Charizard X and Mega Metagross. This said, Avalugg is lacking in reliability, as non-Choice-locked special attackers are able to play mind games with it, mixed attackers can break Sturdy with a physical attack before OHKOing with a special one, and many of the Pokémon it wants to check, like Mega Gyarados, have ways of beating it, like Taunt.

Sawk

Sawk is the fastest viable Sturdymon in 1v1, with base 85 Speed. It hits very hard with its All-Out Pummeling and can check some of the best Pokémon in the meta such as Charizard and Mega Gyarados with its coverage moves. Other options for it include using Z-Bulk Up to counter Mega Gyarados, Choice Scarf to take better advantage of its high Speed tier, and Choice Band to boost its coverage moves like Ice Punch.

Crustle & Carracosta

Crustle and Carracosta both utilize Shell Smash as a method to beat faster and bulkier Pokémon that they would otherwise be unable to deal with. Crustle is the more viable one of the two thanks to its higher base Speed and access to Rock Wrecker, Rock Blast, and Counter. However, Carracosta finds usage due to its access to priority and ability to check Landorus-T and Zygarde. Either one may run Substitute to beat Charm users like Chansey.

Relicanth

Relicanth separates itself from other Sturdymons in 1v1 thanks to its access to Yawn. This, in most battles, essentially allots it an additional turn to KO the foe. Similarly to Crustle, it benefits from a higher power on its Z-Move due to its access to a 150-Base Power Rock-type STAB move. It does, however, lack a Ground-type STAB move and the ability to boost, leaving it quite helpless against Charm users and Steel-types.