You're referring to a Pokémon ROM hack, specifically "Pokémon Sacred Gold" which is a French translation of a hack of Pokémon Gold.
Would you like to know more about a specific aspect of the game or ROM hack? Pokemon Sacred Gold Rom -FR-
As you embark on your adventure, your goal is to become the Pokémon League Champion by defeating the eight Gym Leaders and then the current Champion. Along the way, you'll encounter the nefarious Team Rocket, who are trying to exploit the power of Pokémon for their own gain. You're referring to a Pokémon ROM hack, specifically
The story of Pokémon Sacred Gold (also known as Pokémon Gold and Silver Sacred) is similar to the original Pokémon Gold and Silver games, but with some changes, additions, and modifications. you'll encounter the nefarious Team Rocket