This was written before the Lokix ban, so this may not be up to date.
Analysis
Mawile is a solid physically defensive wall in the current metagame thanks to its Steel/Fairy typing, giving it many key resistances to common types such as Bug, Dark, and Rock while also possessing Intimidate and stifling the strongest of our physical attackers - Morpeko, Lokix, and Cetitan. Mawile runs Stealth Rock, which grants its offensive partners the invaluable chip damage they need to secure more KOs and threaten Rock-weak targets like Yanmega and Chandelure in particular. Play Rough allows Mawile to threaten the aforementioned Morpeko and Lokix, and other Dark-types like Zoroark and Guzzlord. Seismic Toss is an option which avoids Mawile's ordinary passivity, that deals consistent damage, and lets Mawile beat opposing Mawiles in a 1v1 scenario. Baton Pass is key for keeping up momentum and getting teammates like Primarina, Lokix, and Carracosta in safely. Super Fang is another great option which does significant damage to opposing defensive Pokemon ( in particular Milotic, which is then forced to use Recover and leave itself easily taken advantage of by Roserade). Access to Pain Split allows Mawile the option to recover its HP and is particularly effective against high HP targets like Milotic or Guzzlord. The HP taken from the aforementioned targets often constitute a vast majority of the relatively low base HP stat Mawile’s. Finally, Toxic is a great tool for punishing other defensive Pokemon, like Milotic, Avalugg, and Alolan Golem by reducing their signature longevity.
Unfortunately, while Mawile possesses good physical bulk in tandem with its Intimidate ability, its special bulk is especially lacking; ven not very effective hits like Ribombee's Moonblast can 3HKO Mawile which is only able to recover the lost HP via Pain Split. Mawile also cannot run all the moves it would like at the same time, leaving it vulnerable at times to things it is supposed to check. Mawile can alternatively use an offensive Sheer Force Life Orb set; as opposed to its typical defensive set. However, it is too slow to be a consistent offensive threat, and its low base defensive stats are very easy for opposing Pokemon to exploit.
Written by Toy Time King