Pokemon: The Gospel of Gold by GS Lewis

In a re-imagining of Pokemon Gold, a thirteen-year-old novice trainer finds himself caught up in an old conflict of good and evil. The Phoenix, Ho-oh, chooses young Gold as her champion, against the destructive rage of Silver, the Lugia. As he travels the Johto region without any pokemon of his own, Gold learns that the true battle is not of the flesh, but of the spirit.