>>48460538SMUSUM, Platinum, and Emerald are the only games you can call difficult. USUM has strong bosses and Platinum and Emerald have good teambuilding and their Frontiers. I should mention DP is tough too for a first version since it has nice teambuilding too and the game is a bitch if you don't have fire types, making bronzong really threatening, might even be harder than Platinum.
I think after those three I would put SwSh, SwSh's gyms aren't half bad and the dynamax pokemon hit harder than expected, Leon is a letdown though, his charizard is really frail.
