The concept is to blindside the opponent with combinations they won't expect, switching between matchup-based play and setup-based play depending on the opponent's team composition. To the offense-defense core of Mimikyu + Delphox that had been used before, a new axis was added: an Iron Defense + Body Press + Agility Metagross that covers the core's weakness against screen-setup opponents. It was completed by adding a flexible utility pick, Whimsicott (Tailwind/Encore), which helps Metagross stack boosts; a Hisuian Samurott that comes in later to lay hazards; and a steadfast Archaludon that handles Meowscarada, Primarina, and the Charizard line.
The basic flow is to use Whimsicott to neutralize the opponent's halving move with Encore or Tailwind, creating an opening to stack boosts once, and then deploy Metagross. Against Sajabi+Metagross combinations, games were built that are almost unlosable with Metagross under Tailwind, and the fact that Agility keeps its Speed unread was used as a means of turning the game around.