>>47585587to elaborate, bw/bw2 are more like traditional rpgs and random trainers or even wild pokemon could beat you or at least part of your team if you arent prepared, and more difficult fights like gym leaders, although they have less pokemon than usual, are also much stronger than usual and can be a big challenge if you dont have the right pokemon. in addition, theres a challenge mode, which generally makes opponents’ stats and levels higher and gives held items to some more important fights, the bw2 challenge mode champion is one of the hardest pokemon fights ever.
with sm and usum, its a similar situation to bw/bw2, but some trainers use evs and the thing of certain important trainers can wipe you if you dont have the right pokemon applies here even more so. usum is an enhanced version of sm, and although it adds new pokemon to the regional dex that trivialize some early game fights (please dont use hawlucha), it makes some preexisting fights harder, adds a new trial, and adds completely new fights, one of which is one of the hardest fights in any pokemon game