To answer the Rain teams that were popular early in the season and the Steel/Fire Megas that increased from the mid-season onward, the team overturns all weather and centers itself on a Steel-resistant Mega Charizard Y. Its weakness to Stealth Rock was covered by Scizor's field-hazard-removal move, which also has strong matchup performance, and flexible utility picks Garchomp, Primarina, Hisuian Samurott, and Gengar were added to broadly cover Sajabi, Hippowdon, Delphox+Steel combinations, and even Baton Pass.
Scizor clears away Stealth Rock, Reflect, and other field effects to create an environment where Charizard Y can repeatedly deal damage, while Garchomp is used as a stopper that pushes forward from the very first turn. Gengar doubles as a check against Toxic Spikes and Baton Pass, and takes on the role of finishing the game with Perish Song at the very end.