Meanwhile, it's been some time since I've thrown a random odd set that I've come up with that works. This one is pretty effective, though unfortunately I had to drop it from my team due to synergy reasons. But on the bright side, that means you get it now instead of much later after I've smacked people around with it.
Ho-Oh @ Sitrus Berry or other consumable item
Ability: Unaware
EVs: 252 HP / 252 Atk / 252 Def / 252 SAtk / 252 SDef / 252 Spd
Careful Nature or Impish
IVs: 30 HP
- Acrobatics
- Sacred Fire
- Coil
- Roost
The set plays like a fairly typical Unaware sweeper. Set-up alongside your opponent and, once they've realized the error of their ways of trying to boost to +6 in everything, start pwning them. Ho-Oh has naturally high special bulk that lets it handle stuff like Contrary Ytwo, so Coil is the boosting move of choice to both increase its attack power and physical defense. Though Shift Gear and Sword's Dance are options if you'd prefer them.
Normally, Ho-Oh prefers Brave Bird and Flare Blitz. However, on a more defensive Pokemon, these are bad for obvious reasons. So, for Fire, Sacred Fire is chosen as it has good power and a high burn chance that threatens both Shedinja and physical attackers. Meanwhile, Acrobatics might seem like an odd choice. And indeed, using it may cause your opponent to think you're incompetent. But it's actually pretty darn effective since, once the Sitrus Berry is eaten or knocked off, you have a base 110 power STAB with no recoil and high PP. Hilariously, this lets Ho-Oh hit opposing Eviolite Imposters harder than they can hit back, which makes the set Imposter resistant.
If you don't want dual-STAB, I'd recommend opting for Earthquake. Mind, changing out Acrobatics means Imposters become much harder to deal with and removing Sacred Fire drops your Sheddy counter + utility in burning stuff. You can drop Roost to have a surefire way to beat Imposters, provided you're both at high HP and they don't crit, but Ho-Oh will be rather damaged after such an encounter.
While other consumable items could be considered, such as Kee Berry, Lum Berry, Red Card, Weakness Policy, or something else, I found myself preferring the Sitrus Berry as it allowed Ho-Oh to take Gyarados' Crab Hammer or Kyu-B's Extreme Speed and recover enough HP to start setting up in their face. It also lets Ho-Oh switch into rocks more easily if necessary.