You will need a legal Pokémon Emerald ROM and the Quetzal patch, which is frequently updated on community forums like the Pokémon Fan Game Wiki Choose Your Mode:
As a ROM hack, Quetzal requires two things to play: a ROM file of the original Pokémon Emerald and a patching tool (such as Lunar IPS or Floating IPS). You can find the latest patch file from the official Discord server, which has over 100,000 members and serves as the primary hub for updates. Several fan sites also offer prepatched ROMs, though downloading from the official source is always safer. wiki pokemon quetzal
Work together to defeat Gym Leaders or engage in multi-battles against NPCs. 2. Massive Pokémon Roster You will need a legal Pokémon Emerald ROM
The battle system has been updated to reflect contemporary competitive standards: Work together to defeat Gym Leaders or engage
If you want this adapted into a full Pokédex page, fancard, sprite sheet notes, or a short in-universe lore article, tell me which format.