As I develop this universe and the kids and families more I might as well get this one out of the way. Almost anyone, barring medical conditions, can become pregnant and have children in this universe, regardless of gender. This trait has been around for a very long time and most scientists agree it is the result of either some kind of mass magical evolution or interference from some deity. The earlier days of humanity were rough as pokémon and other supernatural entities proved powerful competition and humans needed all the help they could get. Increased birth rates were a huge step in ensuring humanity’s survival, thus the adaptation. (Out of universe, this exists so I can give couples biological children who wouldn’t normally be able to have them.)

In the case of a man becoming pregnant, it has to be planned as the necessary change in biology would take some time to occur. The shift would last throughout the pregnancy then return to normal after the child (or children) is born. The situation is similar for a woman who wishes to get her partner pregnant. There are a number of differences in society due to this adaptation. Gender roles are fairly lax and in cases of family roles and marriage, one’s family lineage typically takes precedence. It’s not uncommon in modern times for a woman to take her husband’s name, but historically and in some regions or families today the spouse from the less prestigious family takes their partner’s name, regardless of gender. There is also typically very little stigma against same sex relationships. In a couple who want multiple children, it is typical for the parents to switch off who has the children. For example, one parent might become pregnant with the first child, and the other parent would have the second child, but it really depends on the couple and what they want. While a female impregnating someone or a male becoming pregnant is always deliberate, accidental pregnancies can still occur in the ‘traditional’ sense, so birth control is still a thing. 

In terms of language, there are probably languages in the world that have different words for a parent depending on if they carried the child or not, but in ‘English’ the words mother and father have no connotation as to who carried the child. A ‘mother’ is a female parent, and a ‘father’ is a male parent. It is important to note however, that adoption rates are fairly low in this world, which is a big issue. A few of my fankids face significant issues in their childhoods because life is quite difficult for those in the system.

Like I said before, this aspect of worldbuilding was mainly to give me more flexibility in the fankids department. It does have an effect on society, but remember it’s not a huge focus, haha.