The idea of the Battle Frontier being reused doesn't seem like fun. :( But the PokeNav's Battle Searcher was nice. It'd be nice to rebattle gym leaders and have the Elite 4's levels increase. Having a voice-automated thing would be cool (you know, recording your voice on your DS). Oh, and the ability to trade Pokemon you've seen (like Darkrai, Arceus) on the GTS without needing an Nintendo event to take place.