>>38726578S/M weren't actually that difficult, the difficulty was just super inconsistent because you were given all these pokemon but the game still uses single battles, which mean if your singular pokemon is effective then you win by mashing A and if it isn't then your opponent wins by mashing A.
On certain playthroughs I demolished the game with a handful of pokemon. On others, my team just didn't counter the typing of the opposition and that gave it bullshit difficulty.
If anything S/M outlined the reasons why Single battles need to go, it causes the difficulty factor be based off things entirely out of your control. You literally just have to be lucky and hope your team counters the opponent. Doubles or triples allows you to use actual team synergy and manufacture your own advantages and wins through manipulation of more than a binary battlefield. In singles the most you can do is bait switchins.