Trainers can use two Pokémon at once, while you can only use one. Essentially, it is a double battle for the opponent but a single battle for you.

For exta difficulty, there is also a version that prevents moves from hitting multiple targets (e.g. Surf, Earthquake).

Demo

Downloads

Use a BPS patcher to apply the patch to the ROM file.

2-on-1 battles

emerald-2-on-1.bps

firered-2-on-1.bps

leafgreen-2-on-1.bps

2-on-1 battles + moves only hit one target

emerald-2-on-1.bps

firered-2-on-1.bps

leafgreen-2-on-1.bps