>>27979830At some unspecified point in the past, humans and the creatures that we call "Pokémon" were once able to lawfully take part together in the religious ceremony and / or legal change of status known as "marriage". And then, at some later unspecified point in the past, the practice as outlined in the previous sentence was either considered too socially taboo to continue due to changing cultural norms or was banned by the authorities outright, although it is more likely that both happened at roughly the same point in time.