See, the thing is I'm totally fine with the "trainers not being able to reject Pokémon Battles" thing but I should think that there could be a bit more complications:
1) I wish we can lazer-eye trainers and battle them and see their already weak Pokémon faint, not like the VS Seeker and variations where we can only battle trainers if they're ready. They certainly never ask us, so why not the other way round? (Could help us a lot in training also)
2) I wish we get some time before the trainers lock us on, so that it would be more "realistic" the way the battle starts. I mean the OW scene of course, because there's no way the two trainers magically warp into a battle ground with lots of space and get some distance between each other. This could possibly relate to using the environment in battles. Also maybe shoo him off to a Pokémon Center once he's beaten, that's a twist.
3) Third thing is, I don't want them to jump in and say, "I like shorts! They're comfy and easy to wear!" and battle us. It's a bit weird the way he tells a random statement and immediately battles us, at least let him tell us his name and say a "let's battle!" variant (though some people do, most don't).