The "251" refers to the total number of Pokémon from the Kanto and Johto regions (Generations 1 and 2). Various versions of this mod exist for different base games, such as and Crystal 251 .
: Some mods tweak gym leader rosters or Elite Four teams to provide a fresh challenge for veterans. How to Install on Android
: All 251 Pokémon are catchable in the wild or via in-game events, including legendaries like Mew and Celebi.
: Many versions include "modern" conveniences like running indoors, reusable TMs, and updated sprites or fonts.