>>45698067As someone who has played every game with the same rules (set, no items during battle, no exp all) I can say that USUM are the most difficult games, with only challenge mode B2W2 maybe being harder. USUM has random 31 IV ace trainers, totem Pokémon that require actual strategy to beat (specifically Wishiwashi, Lurantis, Togedemaru, and Mimikyu), and bosses with 4-5 Pokémon with lots of coverage (Guzma in particular I found tough)