It doesn't -have- to serve as the menu, but giving it some flavour never hurts...*thinking*...duh, what about a Radiation Detector? I'll bet you could easily pull it off with Tetris-esque blocks on small sections of the region map that act as an Itemfinder of sorts for U-DNA-infected pkmn/things and natural Uranium deposits? It could set off danger warnings on the OW screen if you're in a dangerous area, too...[/brainstorming]
EDIT: See, with that idea, for example, it gives you a reason to have a pkpod instead of, for example, a pkgear ebcause it has an altenrate function that can aid you.