Regular Tyranitar is better off performing Stealth Rock support because it has passive recovery in Leftovers. Mega Tyranitar, on the other hand, is best played as a Dragon Dance sweeper because it has the Speed to take advantage of the Speed boost Dragon Dance provides:
-Crunch
-Stone Edge/Ice Beam
-Earthquake
-Stealth Rock/Fire Blast
Nature: Impish/Relaxed
EVs: 248 HP/252 Def/8 SDef
Item: Leftovers
Ability: Sand Stream
or
-Dragon Dance
-Stone Edge/Crunch
-Ice Punch/Crunch
-Earthquake
Nature: Jolly
EVs: 252 Atk/4 Def/252 Spe
Item: Tyranitarite
Ability: Sand Stream
Physically-based Aegislash is crippled by burn very easily. It's best off as mixed, since its Blade forme has equally high offenses and Shadow Ball is stronger than Shadow Claw:
-Shadow Ball
-Shadow Sneak/Sacred Sword
-Iron Head/Sacred Sword/Pursuit
-King's Shield
Nature: Quiet
EVs: 244 HP/12 Def/252 SAtk
Item: Leftovers
or
-Substitute
-Toxic
-King's Shield
-Shadow Ball
Nature: Modest
EVs: 244 HP/12 Def/252 SAtk
Item: Leftovers
or
-Shadow Ball
-Shadow Sneak
-Flash Cannon/Sacred Sword
-Pursuit/Sacred Sword
Nature: Hasty/Naive
EVs: 4 Atk/252 SAtk/252 Spe
Item: Life Orb/Spooky Plate/Spell Tag
or
-Swords Dance
-Shadow Sneak
-Iron Head/Shadow Claw
-Sacred Sword/Head Smash
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Life Orb
Aggron is only good in its Mega form. In its regular form, Aggron is crippled by its common weaknesses to Water, Fighting and Ground. Since Aegislash tends to draw in Fire and Ground moves, Dragonite is a viable substitute:
-Dragon Dance
-Outrage/Dragon Claw
-Earthquake
-Extreme Speed
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Lum Berry/Weakness Policy
Ability: Multiscale
or
-Outrage
-Earthquake
-Extreme Speed
-Fire Punch/Dragon Claw
Nature: Adamant
EVs: 252 Atk/4 Def/252 Spe
Item: Choice Band
Ability: Multiscale
or
-Dragon Claw
-Earthquake
-Extreme Speed
-Roost
Nature: Adamant
EVs: 216 HP/64 Atk/228 SDef
Item: Leftovers
Ability: Multiscale