So, I beat Cynthia. The Base-100 pixies are all really good. It's the bulk that matters more than their offenses, honestly, they could tank like champs. For Cynthia, I set up Leech Seed on her Milotic, then sent in Mew holding a Big Root and proceeded to Calm Mind to +6. Still had to live one EQ from Garchomp, but it did so very well. My team was in the low-mid 60s facing her.
As for difficulty, if you skip trainers AND run 12 mons through the game up to gym 8, you're going to be more-or-less on-par with the boss trainers, or a couple levels ahead at worst. After getting Waterfall, I took my final 6 only and went back through the entire map to 100% the hidden items etc and fought all trainers, and I was slightly underleveled for Cynthia. So the level curve is definitely screwed. Affection /mostly/ wasn't a problem during the game, but it was definitely happening early on, it's just that there were very few fights where I was at all concerned about excess crits mattering. During the E4, it seemed to hit a lot more, though I'm not sure if I passed some threshold during Victory Road, or if it's just that the enemy were launching more attacks so I got to see the miss animation a lot. I generally tried to waste a turn following any good RNG, but not always. Some of the fights required thought, at least. In short? If I want difficulty, I'm going back to No-Dynamax SwSh.