May's Mom was an extra character in "Time Flies" and is the mother of May. She was voiced by Krysdolly.
Whilst in a flashback of his adventures in Hoenn, Ash asked May about her mother, due to her stating her mother wanted her to use protection during sex. May's story "started" in her bedroom, where her mother gives her a "birds and bees" conversation about sexual safety. This was part of a story that basically explains the reason for Misty being a virgin.
Time Flies (Flashback)