Iron Head or Gyro Ball on Aegislash?

Question

For standard Aegislash set

Aegislash @ Leftovers
Ability: Stance Change
EVs: 248 HP / 8 Def / 252 SpD
Sassy Nature
- King's Shield
- Pursuit
- Toxic
- Iron Head/Gyro Ball

Iron Head:
Hits majority of unboosted tier (or anything under 358 speed) for more damage
Can 2HKO standard Clefable and Tyranitar while Gyro Ball cannot

Gyro Ball:
Does more damage to boosted Pokemon
Can OHKO standard/scarfed Xerneas after Stealth Rock while Iron Head cannot
Can 2HKO standard Deoxys-S after Stealth Rock while Iron Head cannot

Is it worth using Gyro Ball to specialize in checking Xerneas or should Iron Head be used for versatility?

Answer 1

It depends on the rest of your team. If you have solid counters to Xerneas, then you can run Iron Head for more versatility. If not, I would suggest running Gyro Ball. Some examples of counters to Xerneas include:
Bulky Fire Types such as Primal Groundon and Ho-Oh.
Poison Types such as Mega-Gengar and Poison Arceus. Mega-Gengar in particular is a good counter due to Shadow Tag.
Bulky Steel Types such as Klefki, Ferrothorn and Jirachi.
Powerful Steel Types such as Mega-Lucario, Mega-Mawile and Mega-Metagross, although these Pokemon struggle to take boosted Moonblasts repeatedly.
Special Defense Behemoths such as Blissey and Lugia.