Okay.... If you can defeat all 100 Trainers of Mt. Battle in either
Single Battle mode or Double Battle mode, Ho-oh will be added
to your PC in your Story Mode file. That's no typo. However,
there are a couple of conditions you have to meet first.
1) You must have fully purified all 48 Shadow Pokémon you can
obtain in the Story Mode.
2) The Pokémon you use must be from Story Mode.
However, there's a workaround to the second condition. You can
use any GBA Pokémon you want, if you transfer them onto Colosseum
first. You can work toward your Story Mode objective and your
Battle Mode objective at the same time, but if you haven't
purified all 48 Shadow Pokémon before you defeat the last Trainer,
you will have to start Mt. Battle all over again.
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