Maybe one that gives useful info, such as a pokemons move lists as you train them and a pokemons base stats? I mean habitat list was a step in the right direction but they could make it a useful item for the next games.
Being able to use it within battle would be neat as well, similar to how it was planned to work in Generation 1.
In the seventh turning hour, should the victims shadows fall, will the irony grow hungry with the victory and all they sought for. We were one among the fence.