It sounds like you're looking for information on , an ambitious GBA ROM hack often hosted on sites like Ducumon.
: Because the original project is Chinese-led, many English versions are "rough" translations or require specific English patches to be fully playable. Download Hyper EmeraldVRainbow Eraserv5d3 ducumon zip
: The "v5" series is known for including nearly all Pokémon from Gens 1 through 8 , including Ultra Beasts, Legendaries, and even diverse variants like Ash-Greninja. It sounds like you're looking for information on
For the most stable current experience, many players look for the on ROM-sharing communities like Reddit's /r/PokemonROMhacks or specialized repositories like PokeCommunity . Are you planning to play this on an emulator or including Ultra Beasts