10 Greatest Pokemon Anime Episodes Ever
7. Bye Bye Butterfree
If you still don't cry at this episode as an adult, you are without a soul. As emotional as the episode's finale is, and boy is it emotional, it comes off the back of what is a pretty standard episode for the original series at this point. That's not to diminish the quality, any episode of Ash's Kanto adventures is better than almost any Unova or Hoenn offering.
What makes the episode special is the number of milestones it accounts for. For starters, the Pink Butterfree was the first time anything resembling a Shiny Pokemon appeared in the anime (though the concept did not yet exist). It was also the first time a character had released a Pokemon, and came less than 20 episodes after Ash first Caterpie, making the event even more of a gut punch.
Most importantly, it showed how Ash will always put his Pokemon's own needs above his desires, respecting them as individuals. He would repeat this with Primeape soon after and many others down the line, shifting him away from his need to catch them all. But still, seeing a member of the team fly away at the height of Pokemania broke a lot of hearts.