Nothing too special/rare, but these are all cards with a story behind them from the collection of my youth.
I remember being 7 years old and zapping on TV, when we came across a boy throwing a red-white ball against a caterpillar, ending the episode (episode 2, where Ash catches Caterpie). Since it looked interesting, we kept looking, and episode 3 started. Me and my little brother both enjoyed watching it.
A couple of weeks later our parents bought us our first booster pack: English unlimited edition Base Set. I don’t know anymore which non-holos it contained, but it did contain a holo Chansey. As a kid however, I didn’t really care about holo cards - all I cared about was more cards. So on the playing ground of school, I traded my Chansey for a Pidgey, Pidgeotto and Vulpix; 1 vs 3 was a no-brainer for 7 y.o. me.
At the end of that same week however, the Pokémon craze was on the 8 o’clock news, where they mentioned some collectors would pay up to 100 Gulden (old Dutch currency) for single cards, and they showed Charizard, and… you guessed it: Chansey. They probably meant 1st edition Shadowless copies of those, but as a kid I had no idea these differences existed, and I doubt the news reporter did either.
A few years back I bought this Chansey for just 2 or 3 USD for nostalgia sake, so here is a picture of those cards:
The next two packs we received about a month later, probably because we had good grades on school or something like that (our parents usually gave use Pokémon boosters as rewards, or as birthday/Sint Nicholas/Christmas presents), were two (English unlimited edition) Jungle packs. Not sure why my local toy shop only sold English boosters, since both Base Set and Jungle were also available in Dutch…
Anyway, those two packs contained a holo Snorlax and a holo Jolteon. I traded the Snorlax for a much cooler Mewtwo promo, but I still have the Jolteon, which is also my favorite artwork of the Jungle set. As a kid I used to reorganize my collection ALL THE TIME. Sometimes sorting them by index, sometimes by type, sometimes by evolutions, etc. Being unsleeved and moved in and out of the binders all the time, the condition is obviously pretty bad. But it’s still nice that I have these original cards from back then, and being played give them some charm for what they are imo.
After that I think I got some Decks, like the (English unlimited edition) Fossil Lapras and Base Set 2 Poliwrath Decks. I also still have both of those cards. I also started collecting Yu-Gi-Oh, and at the time both were about equally exciting to collect/play with. Unlike Pokémon I played Yu-Gi-Oh pretty often with my little brother and friends, and had our mom sometimes translate certain parts of the card we didn’t understand, lol… 
Then a few years forward, we were walking on a market, and I came across a stand where they sold Pokémon booster packs. So, I bought one myself. When I opened it I thought they were fake… It was a Legendary Collection pack, and it contained cards I already had (but with the different set symbol); it contained this very weird looking holo Moltres, which almost looked like a sticker; and to top it off, it contained two of the exact same Slowpokes (it was an error pack)… I was kinda disappointed, because I already had most of these artworks, and it contained two of the exact same card in one pack…
So later I traded the Reverse Foil Moltres for an Ancient Mew; which in turn I traded for a Japanese Neo Genesis Steelix. And fairly quickly I was able to get the Ancient Mew in another trade again, no idea anymore how. (The Reverse Foil Moltres pictured below I bought only a few months ago, for nostalgia sake.)
Fast forward a few years, I remember pulling my very first error card myself. It was a Reverse Holo EX Team Rocket Returns Delibird, with yellow ink smudge on the card and artwork. I was actually pretty excited about pulling an error myself, and I still have it:
One other error I had as a kid, although I didn’t pull it myself (my little brother did), was the EX Sandstorm Marill. Not sure how I discovered it anymore, but one day I noticed my little brother’s Marill had no retreat cost, while mine did. So I traded a card of mine for this Marill, and had both versions. Something which I thought was always cool to have: an error AND a corrected version of the same card:
After that I hadn’t collected in years. Until it was 2014, and I was starting to collect Yu-Gi-Oh again, and played the game online and with my little brother again. We both created a lot of Decks. On the webshop we bought our Yu-Gi-Oh cards (gametimecc.com), there were also a select few Pokémon cards for sale (barely any, probably only about 100 different ones, of which only about 15 actually in stock). I remember having 149 out of the first generations 151 Pokémon as a kid, from opening boosters/decks, trading, gifts, etc. The only two I was missing were Hitmonlee and Venusaur. So, when I came across the webshop trollandtoad.com, where they not only had loads of Yu-Gi-Oh cards, but also Pokémon, I had to get those two. So I bought some Yu-Gi-Oh cards that were out of stock for ages on GameTimeCC, and also bought the missing Venusaur and Hitmonlee simultaneously. So here is a picture of those two, which completed the first gen of 151 Pokémon for me. Both were the cheapest ones available at the time. 
And yeah, that’s basically some noteworthy cards from my youth. I now have over 5000 unique cards including my Pikachus, and another 1000+ duplicates, but these above are some of the cards that really give me a nostalgic feeling. 
