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Bleach and Sunshine, Choice Scarf Metagross isn't a great idea since Metagross isn't fast enough to outspeed all the standards. If you want a fast Metagross, use AgiliGross.
Metagross @Leftovers
EVs: 148 HP / 252 Atk / 110 Spd
Adamant Nature
-Meteor Mash
-Earthquake
-Explosion
-Agility
One of the most popular Metagross sets. Metagross's lowest stat is its Speed, but with one Agility, it can outrun virtually any opponent and wreak havoc with it's awesome Attack. Explosion is great on the AgiliGross as it allows it to take down tough-to-beat opponents even when you are at low health. Thunderpunch is useful since it prevents Skarmory and Gyarados from walling you.
Metagross @Choice Band
EVs: 152 HP / 232 Atk / 16 Def / 108 Spd
Adamant Nature
-Meteor Mash
-Earthquake
-Explosion
-Thunderpunch/Pursuit/Bullet Punch
Another popular set. Meteor Mash and Earthquake cover most of the threats in competitive battling. Again, Explosion is used to go out with a bang when Metagross can't make it anymore. Thunderpunch for Skarm/Gyara, Pursuit prevents foes from fleeing unscathed, and Bullet Punch is a nice surprise for weakened opponents who are faster than you.
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