Max Atk/Spe EVs, Focus Sash guarantees a turn of action so it can reliably do its job — a Mawile build. While the ability Intimidate cuts physical attackers' power, setting up a favorable field with Stealth Rock and Taunt — its composition.

Mega Evolution is generally recommended

It is generally recommended to Mega Evolve Mawile. Its bulk and Attack stats rise, and its ability becomes Huge Power.On top of the Attack boost, its Attack is then doubled, greatly strengthening it as an attacker. Mega Mawile Build Guide and Counters

Alternative Move Options

Boost matchup power with a priority move

Rock Tomb instead of Sucker Punch, to improve its ability to take down the Pokémon it faces, is also recommended. Rock Tomb can lower Speed, so choose according to your preference.

Focus Sash Hazard Setter Role

Brought out as a lead, Focus Sash to survive an attack, Stealth Rock and lay down hazards to support the next ace — its role. Lowering the opponent's Speed Rock Tomb into the mix, creating a field where allies can move safely while disrupting the opponent's setup — core gameplay.

Threats

Weak to Pokémon that break through Focus Sash

This MawileFocus Sash is a Pokémon that does its job while surviving with it, so Fake Out, priority moves, and the like, Weak to opponents that nullify Focus Sash. Keep an eye on the opponent's Pokémon and switch to a teammate against unfavorable matchups.

A Mega Mawile build that maxes out EVs in HP and Attack to fully draw out the high physical Attack from the ability Huge Power. Knock Off and similar moves to chip away at opponents, and uses Swords Dance to boost power further and aims to sweep the whole team — its composition.

Alternative Move Options

The Knock Off slot is a swap candidate

Knock Off slot can run Iron Head or Fire Fang become options. They widen the range of Pokémon you can handle, so swap moves to match the opposing Pokémon you want to take down.

Swords Dance Ace Role

the pre-Mega abilityIntimidate and its excellent type resistances to create favorable matchups, then uses setup moves to raise its own breakthrough power — its role as an ace. Because its Speed is low, after setting up it picks off opponents one after another with the priority move Sucker Punch — core gameplay.

Threats

Weak to high-power special attackers

Mega Mawile has low special bulk and slow Speed, so it Weak to high-power special attackers. It is clearly at a disadvantage against Pokémon such as Fire types that hit it super effectively, so switch to another Pokémon in your party.

Max HP/Atk EVs with a ゆうかん to lower Speed, physical attacker build designed for use under Trick Room Mega Mawile. Before Mega Evolving, the ability Intimidate lowers the opponent's Attack, and after Mega Evolving, the ability Huge Power raises its physical power twofold.

Alternative Ability Options

Hyper Cutter is also recommended

Its pre-Mega Evolution ability Hyper Cutter is also recommended. By using Hyper Cutter as the ability, Incineroar — which has a high pick rate in Double Battles — and its Intimidate.

Alternative Move Options

"Rock Slide" and "Swords Dance" are also recommended

Rock Slide or Swords Dance is also recommended. Adopting Rock Slide makes it possible to OHKO Mega Charizard Y, against which it has a type disadvantage. Also, combining Swords Dance with Sucker Punch, トリックルーム状態 it becomes easier to strike first and knock out the opponent even when it isn't active.

Doubles Trick Room Attacker Role

Before Mega Evolving, Intimidate support and the high firepower after Mega Evolving — fulfilling an ace role that combines both — its role.トリックルーム状態 forces high-power STAB moves onto the opponent, while the priority move Sucker Punch is adopted to Trick Room wears off, it can still pin the opponent down.

Threats

Weak to Fire-type Pokémon

Fire-type Pokémon exploit its weakness, and Play Rough and Iron Head gets halved. Be sure to include a Pokémon that fares well against Fire types in your party. Also, against Mega Charizard Y, Mega Mawile's Rock Slide offers an option to launch a surprise attack.