Mega Metagross is blessed with great Attack and Speed stats, making it a powerful sweeper. Tough Claws boosts most of Mega Metagross's physical moves, further increasing its damage output; in conjunction with a good movepool, this allows it great freedom in the move it sketches and lets it pick and choose among what few counters it has. A good Steel / Psychic typing that gives it a resistance to common attacks such as Extreme Speed offers it many chances to switch in, and decent defenses let it live even super effective coverage without being KOed. However, Mega Metagross is held back by weaknesses to common types such as Dark, Fire, and Ground. It suffers greatly from four-moveslot syndrome, which prevents it from operating at its full potential, and faces competition from other popular Megas such as Mega Pinsir and Mega Gyarados.
Meteor Mash is Metagross's most powerful STAB move, breaking almost anything that doesn't resist it. Thunder Punch hits Water-type Pokemon that can switch into Meteor Mash such as Suicune as well as taking on Celesteela. Ice Punch clocks Landorus-T and Garchomp, allowing Metagross to bypass them while sweeping; it also hits Ground and Flying types somewhat harder than Meteor Mash. Zen Headbutt is a secondary STAB move that hits Pokemon such as Rotom-W that resist Meteor mash without being weak to coverage and lets Mega Metagross fish for flinches to beat counters with. Shift Gear boosts Mega Metagross's Attack and Speed, turning it into a terrifying sweeper on forced switches and weak Pokemon. Bolt Strike, meanwhile, is a more powerful version of Thunder Punch that lets Mega Metagross OHKO Pokemon such as Skarmory and Slowbro at +1. V-create is an option to hit Steel-type Pokemon hard and is stronger than any of Metagross's other moves, but cannot be repeatedly used and leaves Mega Metagross vulnerable to trapping or revenge killing.
252 Speed EVs and a Jolly nature maximize Mega Metagross's Speed, allowing it to Speed tie with other base 110 Speed Pokemon such as Latios and outpace anything slower, including major metagame threats such as Garchomp and Kartana. 252 Atk EVs maximize Metagross's damage output and make it hard to switch into. Tough Claws boosts the damage of Mega Metagross's contact moves, making it harder to wall, while Clear Body is used pre-Mega Evolution to ignore stat drops such as Intimidate ansd Sticky Web.
When fighting versus offensive teams, keep Mega Metagross around until the late-game whenever possible so it can pull off a sweep. Use Mega Metagross liberally versus stall and balance teams to wear down its checks and counters throughout the match. If the foe has Sticky Web on the field or multiple Intimidate users, and Mega Metagross cannot sweep outright, it can sometimes be beneficial not to Mega Evolve and retain Clear Body, but the loss of power is very noticeable. If sketching a coverage move such as Bolt Strike, try not to reveal it the first time an answer such as Slowbro comes in, as they may be scouting for that move and be more cautious with it in the future. Don't switch Mega Metagross in regularly, as while it very bulky it has no recovery, and is vulnerable to being worn down.
Entry hazard setters such as Ferrothorn and Skarmory wear down switch-ins and help Mega Metagross break walls, allowing it to combat stall and balance teams reliably. Other powerful wallbreakers such as Tapu Lele and Kartana are useful to wear down shared checks and counters such as Celesteela. Trappers such as Dugtrio and Magnezone also pair well with Mega Metagross, as they can remove bulky Steel-resistant Pokemon such as Celesteela and Mega Scizor for it. Slow pivots such as Rotom-W and Landorus-T are handy to bring in Mega Metagross safely on Pokemon that it beats, like Clefable and Venusaur. Status absorbers such as Chansey and Clefable are also good teammates, as they can take Will-O-Wisp and Scald for Mega Metagross.
Heavy Slam is another option to hit hard right off the bat but is switch-in bait for heavy Pokemon such as Celesteela and doesn't add any coverage. Swords Dance is a decent Sketch option to make Metagross immensely threatening, but outspeeding faster Pokemon such as Pheromosa is generally more important. Bullet Punch can be used to give Mega Metagross a way of revenge KOing faster foes, particularly on Sword Dance sets, but base 110 Speed is usually enough for most purposes and Metagross needs the coverage.
Hammer Arm and Earthquake can both be used to hit Steel-type Pokemon without sketching V-create, but they are weak and easy to wall. Power Whip may be used to hit Water-type Pokemon hard while covering Quagsire but is weaker and cannot take out Celesteela; Grass Knot does a similar job while freeing a sketch move. Sketching a recovery move can be handy on balance teams for more longevity and opportunities to switch in, but Metagross usually prefers coverage or setup. U-turn is a decent sketch move to wear down switch-ins and gain momentum, but it does little damage and is usually suboptimal compared with hitting switch-ins super effectively.