Pokémon - Image #659,751

You're forgetting the very important fact that Pokemon writers, simply don't give a fuck.
This character here is introduced in an episode in Pokemon Chornciles in which Brock returns to Pewter City after the Johto league is over, he, along with all of his siblings refer to her as mom, Flint refers to her as his wife, and there's even a flashback with Flint and her when they were young.