It sounds like you're referring to Pokémon Brick Bronze , a popular Roblox game that was taken down years ago due to copyright claims from Nintendo/Game Freak. An version would mean a copy of the original game file with full editing permissions — however, those files are not legally available, and sharing them would violate both Roblox's terms and intellectual property law.
At its peak, Pokémon Brick Bronze was attracting over 100,000 concurrent players. It wasn’t just a game; it was a social hub. For many young Roblox players, it was their first introduction to the Pokémon franchise, or at least the first place where they could experience a Pokémon adventure with friends online. It validated Roblox as a legitimate game development engine, proving that "kids' blocks" could build complex worlds. --- Roblox Pokemon Brick Bronze Uncopylocked
This brings us to the core of the keyword: It sounds like you're referring to Pokémon Brick