I know a lot of us either watch the show now or have fond memories of watching it at some point during our Poke-Obsession. Share your favorite episodes from the anime classic. 
A few of mine:
. Ignorance is Blissey
. Mystery at the Light House
. The Ghost of Maiden’s Peak
. The Tower of Terror
. Holy Matrimony!
. Attack of the Prehistoric Pokemon
. Go West, Young Meowth
I only watched the English version. I had a fond love for the Haunted house episode and the introduction of Scyther. Introducing Mewtwo too was awesome. When James kicks his Magikarp and a flock of Gyarados shows up.
One episode that still escapes me though. When we see Brock for the first time after he stayed with the Breeder. There was no explanation to what happened. Brock was just alone and sad but it was never said why. Did they explain that in the Japanese version?
“Friends to the End”
I’ve always loved paranormal movies and shows, obviously! Morty is my favorite gym leader, Ecruteak City is my favorite city and Johto is my favorite region.
The one with Charizard in it…And…Bye Bye Butterfree
I also like:
Never had an opportunity to watch seasons 4 or 5 unfortunately
Havent seen the show since the neo era but the squirtle squad episode will always be my favorite.
I don’t watch too much of the show but I love the older movies…The Power of One (Pokemon Movie 2000) and Destiny Deoxys are my favorites. Some of the humor in The Power of One is directly aimed at adults and is pretty superficial but hilarious.
It’s funny how most of us have the same favorites 
Easily The Tower of Terror, Abra and the Psychic Showdown and Island of the Giant Pokemon. Of course Ghost of Maiden’s Peak comes to mind, too.
Pokemon - I Choose You! Was what made me a Pokemon fan so it holds a special place for me. It aired on November 1999 here.
I love the St. Anne episodes too as the original Finnish dub is filled with puns and funny jokes all around 
But honestly the whole first season is filled with good episodes.
The episodes with Ash getting all the starter Pokemon for some reason are one of the most nostalgic ones for me. I think they were all quite well made with each starter having their own background and having their own personality. On Bulbasaur and the Hidden Village there was something heart warming on the episode as a kid, I liked how Bulbasaur wanted to protect the weaker Pokemon that lived in the village and Misty apologizing to Oddish was a memorable moment as well. Charmander’s episode was very touching too as he was treated very unfairly by his original trainer. In the end I think that episode helped Charmander to become my favorite starter, he seemed like such a sweet Pokemon but he was very powerful inside when he believed in himself. Here comes Squirtle squad is another funny episode and I think it was a genius idea to make a Pokemon gang like that.
Attack of the prehistoric Pokemon is a good episode as well, and probably is an iconic one for the fact how Charmeleon evolved into Charizard. I thought he evolved because he wanted to protect Ash but it was just to compete with Aerodactyl lol. Ash’s battle with Blaine is also what really made me like Charizard later on even though he was kinda a douche.
Bye bye Butterfree is so legendary too, I think there’s no need to explain. Meanwhile I found all the episodes with Sabrina to be creepy, I didn’t like those very much back then. Also, to name some episodes I don’t like, I hate the Kangaskhan kid episode. I don’t know about the English dub but the kid and his parents were super annoying in the Finnish version.
It’s hard to name favorite episodes from the Johto era as they skipped so many episodes from them here but the ones where Ash was competing on the league are memorable (also, the Orange Islands season was completely skipped here). From Hoenn episodes though I like the ones were Team Aqua and Team Magma appear with Groudon and Kyogre and Pikachu gets affected by Red / Blue orb I think? I used to think it was cool because it was something we usually only saw during the Pokemon movies.
I really haven’t watched the Pokemon anime after the DP seasons. It kinda ended for me because I didn’t like Ash’s companions on BW and lost interest to keep following the anime, but I love to go back to the older episodes from time to time. I think the Finnish dub has something to do with it as well, in the first seasons we had a great dub and amazing translation team behind it to make it work. Nowadays I think they are trying too hard to be funny and the voice acting isn’t as good as it used to be so it’s also a factor why I don’t really follow the anime anymore.
Whoop. I didn’t mean to write a wall of text but it happened xD
I watched bulbapedia.bulbagarden.net/wiki/EP088 last night, I tend to like episodes with rare and odd Pokemon in them
The episode with the pink butterfree. I almost cryed when it flew away at the end.