Pokemon Crystal 251

Pokémon Crystal: 251 is a vanilla Pokémon Crystal hack which allows players to catch all 251 monsters and collect all the special items without the need for a game-link cable. While this was specifically created for play on emulators, it is considerate of players who would like to flash the rom to real cartridges for use on real hardware, and changes nothing which might create incompatibilities. The patch DOES NOT make any attempt at changing or introducing any new evolution methods, sprites, monsters, attacks, difficulties, settings, features, etc… This patch is purely focused on playing through the classic Crystal with organic solutions to not having game-link abilities.

Source: TheGamesDB