Mine was Ready, Willing, and Sableye, a filler episode from early Hoenn that I watched when I was six years old, I think. I remember being really confused as to who Team Rocket were because I wasn't familiar with them (I had only played Sapphire at the time), and had also never seen a Meowth before. Since Team Rocket didn't interact with the main characters or any Hoenn Pokemon for a couple minutes, I initially thought the broadcaster had accidentally switched to another show, haha.