Latias-Mega @ Latiasite  
Ability: Levitate  
EVs: 36 HP / 252 SpA / 8 SpD / 212 Spe  
Timid Nature  
IVs: 0 Atk  
- Calm Mind  
- Roost  
- Charm  
- Shadow Ball  

Hoopa-Unbound @ Darkinium Z  
Ability: Magician  
EVs: 252 HP / 36 Atk / 76 Def / 60 SpD / 84 Spe  
Jolly Nature  
- Hyperspace Fury  
- Gunk Shot  
- Taunt  
- Dark Pulse  

Metagross-Mega @ Metagrossite  
Ability: Tough Claws  
EVs: 200 HP / 92 Atk / 100 SpD / 116 Spe  
Adamant Nature  
- Meteor Mash  
- Bullet Punch  
- Laser Focus  
- Rock Tomb  

 Latias
    Lives 2 Shadow Balls from 252+ Mew and sets up on it.
    Beats Victini
    Beats Choice Specs Necrozma
 
 
Hoopa-Unbound
    OHKOs Every Poke in the tier with z-Hyperspace Fury bar Gardevoir-Mega and super bulky Metagross-Mega
    OHKOs even 252/252 Mega-Metagross with z-Dark Pulse.
    OHKOs Gardevoir-Mega with Gunk Shot.
    Outspeeds base 100s with 4 speed evs or less.
    Lives a 252 Hoopa-Unbound Signal Beam and OHKOs back with z-Hyperspace Fury.

 
Metagross-Mega
    Lives a 252+ Dark Pulse and a 252+ Hyperspace Fury from Hoopa-Unbound and KOs back.
    Beats Mega-Gallade
    Beats Mega-Gardevoir
    Beats Colbur Berry Necrozma