Japanese culture believes that things created by people have a sort of spirit attached to them, and a masterful creator can imbue a particularly strong one in his or her creations. Objects owned by people and cared for can eventually take on a life of their own.
Thus, Pokemon based on objects are fully possible and very likely considering that they are a part of Japanese folklore.
"Murder of the living is tragic, but murder of the idea is unforgivable." - Janus, speaker of the synod