They have had Pikachu eating ketchup a few times since then, one episode in particular that I can remember is "Air Time", but I know they've done it in AG too. Anyway, this is one of my favorite episodes. This particluar period in Kanto produced some really good ones. Both Elactabuzz and Scyther made their debut in this one, and that's saying something because they're really cool pokémon. The ketchup thing was hilarious, and it was really cool to see Brock use Vulpix since it was severely neglected most of the time. The Nurse Joy inspecting the two gyms for the pokémon legue was a cool idea, and I actually didn't see it coming. The fight between the Yas and Kas gyms was cool, and I thought the animation on Pikachu's thunder attack was really awesome. There's also so much comedy in this episode, like Ash saying his name was Tom Ato.XD I also like Ash's lecture to the Yas and Kas gym leaders. It was something like this:
Ash: You battle with all your strength trying to win.
Kas Gym Leader: With all your strength? Isn't that the same as fighting?
Ash: No, it's completely different. Of course you try to win, but you don't try to beat each other!
Gym Leaders: Huh?