[Honestly, she should probably think of other ways given how this cave effects their pokemon, but she would love to have a battle. That said, something Lucas says brings a question to mind.]

You said you'd been here for a little while, right? I'm surprised you haven't already treated it.

[But there has to be an explanation for that, so...]

That must mean there's something preventing you from reaching it, right? Another pokemon protecting it, maybe... Or maybe even the strange effect this cave is having on our partners.