In a Romlocke, all Pokemon, including legendaries are replaced with those of fakemon. There are many ways of doing this, for example, you can easily inject fakemon into your game using rom hacking tools within minutes. This tool is called PGS and you can quickly import and export Pokemon from one game and import them on another.
Recomended Versions for Romlockes are third generation games, preferably Ruby and Sapphire,Fire red and leaf green this is due to the chance of emerald glitching with battle animations. previous games such as first and second gen games can be used, but to my knowledge, I do not know anyway of exporting and importing fakemon. Later games such as Diamond and Pearl, are not yet fully supported by rom hacking tools and therefore isn't conventional to use.
Now that you have Fakemon imported, you may want to use the Univeral Pokemon Randomizer, as it sorts out the placing of pokemon.
Standard Nuzlocke rules apply to the Romlocke, these include, but are not limited to:
- Any Pokémon that faints is considered dead, and must be released or put in the Pokémon Storage System permanently.
- The player may only catch the first Pokémon encountered in each area, and none else. If the first Pokémon encountered faints or flees, there are no second chances. If the first encounter in the area is a Double Battle in dark grass, the player may choose which of the two Pokémon they would like to catch. If there's a static encounter in the area, the player is allowed to capture them despite already capturing a Pokémon in that area. Shiny Pokémon also do not apply to this rule.