I’m afraid it’s merely a legend, anonymous. There aren’t any solid records of this actually happening.
As for my opinion concerning it, my explanation of poképhilia in modern times aside, it would certainly be interesting. I say “interesting” because it could indicate one of three things:
1. Pokémon were far more intelligent then than they are now and were capable of both communicating and understanding humans fully.
2. Pokémon and humans were far, far more alike than they are now (which itself could imply that humans had been a sort of pokémon or very close relatives to them before evolving away from that state).
3. This says more about humans and human morality than about pokémon.
Either way, the point is, it would be either anthropologically or ethologically fascinating to study.