I went through the normal title sequence, though this time, I couldn't select the girl gender, but I didn't mind, seeing as I'm a guy, and I knew that that was one of the changes from Blue to LeafGreen. I chose "Red" as my name, just because I didn't have any ideas whatsoever. I played through the game like normal, beating the gym leaders and then the Elite Four. Most of my Pokémon were around level 60 or 70, but I felt that wasn't enough, so I used the infamous Missingno. glitch to catch one, and to get myself infinite rare candies. I leveled all my Pokémon up to level 100, then I leveled up Missingno. to level 255. Curious, I leveled it up once more, knowing that it would just go down to level 0 and become very glitchy, but instead it leveled up to level 256.
Knowing that this was impossible, I quickly jumped to the assumption that I had an earlier version of the game that had a few bugs. I checked the Missingno.'s stats, and weirdly enough, they were all at 0; so was his HP. The only move it knew was Splash. I was starting to think that maybe my game wasn't actually a real copy of Pokémon Blue, that it was some bootleg version of Pokémon that was meant to be glitchy. I tried it out in a battle against a wild Pidgey, but instead of one-hitting my extremely weak Missingno. with Tackle, it stated on the screen "Wild Pidgey's attack didn't work!". I tried using Splash out of curiosity, and I really wished I hadn't.
When I selected it, the screen suddenly flashed black, and Splash was replaced with the move "256". I selected the oddly named move, and the Pidgey was immediately forced out of the screen as if the move Whirlwind was used, followed by the cry of Pidgey. However, the cry was extremely distorted and played at a low frequency. Once the cry was finished, the game displayed the message "Wild Pidgey was overpowered!", followed by the typical "battle over" sequence. At this point, I tried turning off the game, but nothing happened. The game then stated "Missingno. used 256!", even though I was in the overworld and the battle was over. My overworld sprite then disappeared. I tried walking around, but nothing happened.
I could still access the menu, so I went to view my Trainer Card. The option no longer said "Red" but instead displayed my name as "...". I viewed the card, and my player sprite was replaced by nothing. Literally, nothing. All my gym badges were gone, too. So were my items, Pokémon, and money. My game then shut off automatically. I ripped the cartridge out of my Gameboy and posted the game on eBay for 5 bucks. About a week later, someone bought it. I will never play another Pokémon game for the rest of my life.