Retired Pokémon in the main anime?

Say, I think that some of the Trainers' Pokémon retire from the battle due to any reasons, like excruciatingly weaker body muscles and slower rate speed, and entirely forgotten moveset. You think?

One of the first Pokemon that came to mind was Tracey's Scyther, though I know he battles with on occasion. Still, it usually doesn't last as long in battle due to its age, so it wouldn't surprise me if it were near the end of its battling days.