ThxLevel cap is increased, but I'm pretty sure enemies just scale with your level, so it doesn't make it any less challenging.
But DLC2 also added very powerful mons that non DLC2 trainers don't have access to.
You can probably steamroll them with Tangleplant and Gelien who snowball extremely hard against most enemies.
Well, not using new mons is doable compared to having extra levels lol