The 1980 anime
Maeterlinck's Blue Bird: Tyltyl and Mytyl's Adventurous Journey has some male, female and animal AR in episode 19.
The villain in the episode is a monster whose breath makes stuff younger. The video I'll link to is in Italian, so I don't know the context, but when the protagonists (Two children, a male anthropomorphic dog and a female anthropomorphic cat) fight it, they get turned into babies. There's even some nice and adorable process as they shrink out of their clothes.
Later in the episode, an old woman makes herself young again to fight the monster, though there's unfortunately far less process on her part, as it's quick and a lot of it is a fade.
https://www.youtube.com/watch?v=Jm6y0-rYmhc
(I know it's already on the TF Theater site, which I assume most members of the Process forums already visit, but just in case, I'm mentioning it here for convenience's sake. ^^")
Finally, I deserve no credit for this find; huge thanks to Tazz for finding this adorable sequence and sharing it!