Mega Aggron @ Aggronite
Ability: Sturdy/ Filter
EVs: 252 HP 252 SpDef 4 Atk
IVs: 0 Spe
- Stone Edge
- Sleep Talk
This set allows Aggron to act as a Tank/Wall. His naturally high defense needs no investment, so maximizing HP and Special Defense is recommended. A Sassy nature is used so he can hit Aegislash in Blade form 100% of the time, allowing a clean KO. Rest and Sleep Talk are his only real forms of recovery, but they get the job done. Stone Edge and Earthquake are used to allow him to hit most of the tier for neutral damage.
An alternative option is to run a full out attacking set, with Earthquake, Stone Edge, Fire Punch, and Iron Head/ Heavy Slam. This forgoes his walling abilities and instead turns him into a powerful Physical Tank.
Checks and Counters: the best counters to Mega Aggron are Mega Lucario, Excadrill, and Garchomp.
Mega Lucario at +2 is a clean OHKO, both with Close Combat on Physical sets, and Aura Sphere on Special sets.
Excadrill can hit Mega Aggron with two Earthquakes in a row, as long as it hold Air Balloon. Mold Breaker prevents Filter from reducing damage, allowing a 2HKO most of the time.
Garchomp is more of a check, but can still deal a significant amount of damage with Earthquake or Fire Blast. Mega Garchomp hits particularly hard with Fire Blast, thanks to his increased special attack.
Overall, Mega Aggron is one of the best physical walls in the game, and with Filter, can take a few weaker special super effective attacks.