On Christmas in 1999, my mom and I visited my grandma, along with my aunt and her son who was into Pokémon, in the evening. When we were opening up our presents, I had gotten Pokémon Yellow to play in the Game Boy Color that my mom had gotten me for Christmas, which I began playing with Super Mario Bros. Deluxe earlier in the day. Given how I am about Christmas presents, I was kind of meh about it, but I was told that I would like the Pokémon game.
After I got home, and loaded Yellow for the first time the next day, I got hooked on it instantly. On the earliest playings of Yellow, though, as I was a new trainer, I did make some crucial mistakes, including spoiling my starter Pikachu (to the point where it got to Level 65 by the time I reached the final Gym), and ignorantly trying to use electric attacks against Brock's Pokémon, as well as trying to catch other trainers' Pokémon, especially those that couldn't be found in the wild in that particular version (such as Team Rocket's Pokémon and Bug Catchers' Weedles). Early on, when I was struggling to defeat Brock, I thought that the only way to be effective against him was to trade for a Bulbasaur or Squirtle from Red or Blue.
A sour moment early in my experience playing Generation I was when my save file from Yellow got "destroyed" on Labor Day 2000. Now that I think about it, though, it was probably a blessing in disguise, since it wiped out all the critical mistakes, including those I mentioned above, that I made while playing that file (Additionally, I ran from all three Legendary Birds, both Snorlaxes, and even wasted my Master Ball on a Farfetch'd after getting frustrated at it breaking out of my Great Balls.)
At some point in mid-2000, I got Blue, my second main series game. It would still be awhile until I got a chance to hook up to my cousin's Game Boy Color to trade with him. Most of the time when I did that, though, I traded between two of my own games.
When I finally read about how to execute the MissingNo Old Man Glitch in a game cheats magazine, I really went for it in Blue, exploiting the glitch to clone Master Balls, Nuggets, and other items that couldn't be bought at PokéMarts. Within the next couple of years, though, I would also battle the level 147 Golducks that came about from the glitch, primarily to help get my team to level 100 for Pokémon Stadium's Prime Cup.
I traded in Blue, Yellow, and all my other Pokémon games in January 2006, when I decided to try and get out of Pokémon gaming. I had been feeling a bit burned out playing the main series games for at least a year or two prior. This is actually a decision I've since come to regret at times, but now I'm looking forward to purchasing the Virtual Console releases of the Generation I classics on my 2DS (which I bought used in order to get back into Pokémon gaming on an actual Nintendo system) when they do come out.