>Maison
v
>Subway
v
>Tree
v
>Frontier
v
>Tower
v
v
v
>Tower (SwSh)
Special mention
>Arena (multibattle)
>Facility
The hardship of the battle facilities aren't determined by NPC's IV, EV, Abilities or hold items because all those things have been rigged since the beginning. NPC will always have 100% IV mons with impossible EV stats, beneficial Natures and Abilities, and perfect combination of hold items. The one that makes them harder than the rest is their AI level. I played most BF in all Pokémon games so I ranked them based on the difficulty that I faced. Maison and Subway are peak difficulty to the point of annoyance and depression. The only reason why Tree is slightly easier because GF received complaints about the difficulty of Maison. But they did fixed the Truant Durant trick though. So for me, Battle Tree is comfiest of them all. I expected GF would slightly increase or retain the difficulty of Rose Tower but instead they made it so much easier, which is disappointing and counterproductive.
