Ideally, it'd be like SMT or Persona: Very stylish and trendy, not shying away from topics like sex, crime, and violence but not necessarily reveling in them either. It'd presumably still be a turn-based JRPG, so the battles themselves wouldn't be overly gory, although cutscenes also wouldn't be afraid to show trainers and Pokemon get messed up. Really, I imagine it'd turn out kind of like Colosseum, except it wouldn't beat around the bush at all with regards to the seedier elements of society.
Realistically, we'd probably get something like "The Mature" in
>>49477521, because the idea of "lol it's a game for children but it's violent" would be too tempting for whatever hacks ended up making it. See also: Every shitty Youtube video about Mario doing drugs and shooting Koopas with guns.